You Know Who

James Sirius Potter was the eldest child of Harry and Ginny Potter. His godparents, as well as uncle and aunt, are Ron and Hermione Weasley. He has two younger siblings: Albus and Lily. James was named after his paternal grandfather, James Potter, and his father's godfather, Sirius Black. 

James was seen going to Hogwarts School of Witchcraft and Wizardry on 1 September, 2017 with his brother Albus, who was just starting his first year. James, being the oldest child, had already been attending Hogwarts, but it is not specified which year he was entering. Contemporaries at school include his cousins Victoire and Rose, as well as Draco Malfoy's son Scorpius, though they are in different years.

When his family was gathered to see him and his brother off at King's Cross Station on 1 September, 2017, James interrupted his cousin Victoire snogging Teddy Lupin, and then ran off to tell his family and other relatives. He was disappointed when they did not react strongly. At some point, James would also steal the Marauder's Map from his father's desk drawer, while he was not looking, to have fun with it at Hogwarts.

James is much like his uncle, Ron, for his poor timing and knack for interfering with other people's love lives. He also seems to have inherited his sense of humour and love for mischief from his two uncles, Fred and George, and having a fondness for teasing his siblings and making mischief. He is also very much like his two namesakes, James Potter and Sirius Black, in his mischievous and trouble-making nature. 

James has a strong connection with both of his parents, even though he does not want to show it in front of other people, especially girls and friends. Still, he permitted his parents hugs and kisses (from Mother) before rushing off to the Hogwarts Express in 2017, and wrote to them three times a week the previous year at Hogwarts School of Witchcraft and Wizardry.

Albus Severus "Al" Potter (b. between 1 September, 2005 and 31 August, 2006) was a half-blood wizard and the second son of Harry and Ginny Potter (née Weasley). Albus is the middle of three children, born at least a year after his older brother, James, and two years before his younger sister Lily. He was named in honour of Albus Dumbledore and Severus Snape.

On 1 September, 2017, Albus left for his first year at Hogwarts School of Witchcraft and Wizardry along with his cousin, Rose Weasley, as well as Scorpius Malfoy. Before boarding the Hogwarts Express, Albus confided to his parents that he feared he might be sorted into Slytherin. In response, his father told him that the bravest man he ever knew — Severus Snape, whom Albus was named after — had been a Slytherin. Harry also assured his son that, if he was sorted into Slytherin, then the house would have gained a good student and that he and Ginny would think no less of him for it. Harry also told Albus that if he preferred Gryffindor, then the Sorting Hat would take this choice into consideration, as it had in his case (something Harry never told any of his other children). At this, Albus' face was described as being in 'wonder.' 

Albus takes after his father in appearance, meaning that he has untidy hair, and has bright green, almond-shaped eyes. He was the only one of Harry's three children to have inherited his paternal grandmother's eye shape and colour.

Unlike his rowdy, outgoing older brother, Albus seems to be a quiet and thoughtful boy. He is marked by insecurity and seems to have an especially close relationship with his father. He sometimes doesn't understand why people stare at his father and finds it very interesting when they do.

Albus has an especially close relationship with his parents. When he felt insecure about attending Hogwarts for the first time and worried he would be in Slytherin, his father comforted him, and his mother did likewise when his uncle Ron teased his cousin Rose about getting disinherited if she wasn't sorted into Gryffindor house. Though the boys are close in age, James has a more outgoing personality, while Albus is quiet, and more like his younger sister. All three siblings share the opinion that Teddy Lupin would make a great addition to the family if he eventually married Victoire Weasley. Albus and his cousin Rose Weasley are close in age and in the same year at Hogwarts. Just like Lily and Hugo, they seem to be quite close, and shared worry over where they would be sorted. When Rose arrived at King's Cross Station to head off to her and Albus' first year, Albus was "immensely relieved" to see her and Rose beamed at him.

 Lily Luna Potter (born between 1 September, 2007 and 31 August, 2008) was the only daughter and the youngest child of Harry and Ginny Potter (née Weasley). She had two older brothers; James Sirius and Albus Severus. She was named for her paternal grandmother and also her parents' good friend, Luna Lovegood.

Lily Luna Potter was born to Harry and Ginny Potter as their youngest child and only daughter. She has two older brothers: James Sirius and Albus Severus Potter. Lily is around two years younger than Albus, who is at least a year younger than James.

In 2017, she went to see her brothers and her cousin, Rose Weasley, off at the Hogwarts Express, but was not herself old enough to attend Hogwarts School of Witchcraft and Wizardry. She also acted as her mother Ginny Weasley had acted when Harry and Ron went to their first year of Hogwarts. She and her cousin, Hugo Weasley, are around the same age, as Hugo is also not leaving on the train to school. 

Lily is described as having red hair. It is known that Lily does not have green eyes, as Albus is the only child with that physical trait. Lily takes after mostly her maternal family (and her paternal grandmother) in looks, rather than her older brothers, who take after their paternal family. 

Lily seems to have a personality similar to her mother. She is very jealous of her two older brothers when they are leaving for Hogwarts, quite similar to the eagerness and envy Ginny displayed when the last of her brothers went away to school in 1991. She seems to enjoy talking to her family. She and Hugo, her cousin, had an "animated discussion" about what house they would be in. 

Lily is shown as having a close relationship with her father and her mother; she resembles her mother, Ginny Weasley in appearance and personality. She also seems to love her father dearly, and was holding hands with him in 2017. James seemed to have a fondness for teasing his younger siblings. Lily went to see her brothers off at the Hogwarts Express in 2017. Hugo, Rose, and Victoire Weasley are probably the cousins Lily is closest to. In addition to being the same age, she and Hugo excitedly discussed Hogwarts in 2017. Lily was thrilled when she heard about the relationship between Victoire and Teddy Lupin. Teddy Lupin was Lily's father's godson. He often spent time at the Potters' home, and Lily was very excited at the news that he was dating her cousin Victoire. She hoped that they might marry so that Teddy would become an official member of the family. This is very similar to Ginny's longing to have Nymphadora Tonks, Teddy's late mother, in her family, deepening the connection between Lily and her mother. 

Rose "Rosie" Weasley (born c. 2006) was a half-blood witch and the daughter of Ronald Weasley and Hermione Granger. She had a younger brother named Hugo who was born about two years after her. She began attending Hogwarts School of Witchcraft and Wizardry in 2017, the same time as Albus Potter and Scorpius Malfoy, and, being a Weasley, may have been Sorted into Gryffindor.

As Rose prepared to go off to her first year at Hogwarts School of Witchcraft and Wizardry with her cousin Albus Potter in 2017, her father encouraged her to be sorted into the same house as himself and her mother, Gryffindor. He also jokingly told her to beat Draco Malfoy's son, Scorpius, in every test, though Hermione expressed a more tolerant attitude. Ron also warned Rose not to get too friendly with Scorpius, quipping that her grandfather, Arthur Weasley, would never forgive her for marrying a pure-blood. 

Rose seems to have a strong relationship with her father, Ron Weasley, as they were joking about the Hogwarts sorting. Rose is also thought to be close to her mother, Hermione Granger, as they have many of the same qualities, such as intelligence. She's also close to her cousin Albus as she beamed at him. Rose is assumed to have a good relationship with her brother and cousins. 

Rose is said to have inherited her mother's intelligence. It is also noted that she put on her robes before needed, like her mother did at her age. If her father's encouragement to beat Scorpius Malfoy academically has any effect, she may also turn out to be rather competitive and academically brilliant like her mother. She seems to be quite close to her cousin Albus, Harry and Ginny's son, who is about the same age and who shared her anxiety about where he would be sorted at school. When she arrived at King's Cross Station to head off for their first year, Albus was "immensely relieved" to see her, and Rose beamed at him. 

Hugo Weasley (born c. 2008) was a half-blood wizard and the youngest child of Ronald and Hermione Weasley. He had an older sister named Rose and attended Hogwarts School of Witchcraft and Wizardry, possibly with his cousin, Lily Potter. As a Weasley, it is likely Hugo was Sorted into Gryffindor, but this is unknown.  

Hugo Weasley was born in late 2007 or early 2008  to a pure-blood father and a Muggle-born mother. He is about two years younger than his sister Rose, and around the same age as his cousin Lily Potter, daughter of Harry and Ginny Potter, and the two seem to be quite close. In 2017, he accompanied his parents to see off his sister and Potter cousins to Hogwarts School of Witchcraft and Wizardry. Hugo and Lily shared an eagerness to go to Hogwarts, despite both of them being too young. The two had "an animated discussion about which House they would be sorted into when they finally went to Hogwarts" at King's Cross Station.

Hugo is a Latinised form of the Germanic or Teutonic name Hugh, meaning "bright in spirit and mind". French novelist and poet Victor Hugo was a famous bearer of this name. It is possible that Ron and Hermione wanted their children to have the same first initials as they have, R and H. It is also possible that they named their children after Hermione´s parents or grandparents, or after Ron´s maternal ones.