Later life. It is known that the last living Gaunts by the summer of 1925 were Marvolo and his children Morfin and Merope. It follows that Ominis had already passed away by that date; he either did not have any offspring or, if did, they must also have already died by that date.
The Harry Potter book series, which is counted as the main source of canon, is pretty clear about the fate of the Gaunt family; as already mentioned, they had all but died out by the time Voldemort was born, so it is likely that Ominis had already died by then.
In fact, it's highly likely that Ominis Gaunt is Voldemort's great-uncle in Hogwarts Legacy. One of Ominis' older siblings, who tortured him with Crucio (an available spell in-game) is thought to be Marvolo Gaunt, who eventually had two children. His daughter, Merope Gaunt, went on to marry Tom Riddle Sr.
By the end of the game, Sebastian and Ominis are still friends, albeit their relationship markedly changed due to in-game events. Though they are no longer as close, the door has been left ajar for the two young wizards to strengthen their bond someday, and I hope we get to see it in a future Sebinis (Ombastian?)
Morfin, returning from his three-year sentence, then succeeded Marvolo as the patriarch of the family. Morfin lived, as the last male heir to the Gaunt name, in solitude for the next thirteen years, with very poor care of his hygiene and household, causing both his appearance and the shack to deteriorate drastically.
He's always going to have a showdown with his uncle after he goes too far down the dark magic rabbit hole, and eventually he uses the killing curse on him. None of this changes, the only difference is that you can choose whether or not to turn Sebastian in for killing his uncle or not.
If you're horrified by Sebanstian's blatant use of outlawed magic, you can turn him in soon after the quest to see him expelled from Hogwarts and thrown into Azkaban for the remainder of the story.
Harry, as heir of Gryffindor, possessed the love of this Muggle-born woman in his very blood and was the perfect champion to stand up against the heir of Slytherin.
Determined to keep the family line 'pure' and pass down certain Slytherin skills, such as Parseltongue, the Gaunts had a tendency to marry their cousins, as Albus Dumbledore observed.
What happens to Sebastian Sallow if you turn him in?
If you turn Sebastian in, he will be expelled from Hogwarts and you will not be able to interact with him again in the game. This means that, if he hasn't already taught you the Unforgivable Curses, now he never will. He will be taken to the Ministry of Magic to face justice.
This choice doesn't affect the main story or Hogwarts Legacy's ending, so it really is just up to the player to decide which character they'd rather go with.
Should You Turn Sebastian In Or Not? Players who chose not to learn the three Unforgivable Curses when they had the chance earlier but want to learn them now should choose not to turn Sebastian in; once he is gone, the only way to acquire these spells is for players to begin a new game and start over.
You shouldn't turn Sebastian in because it brings more restrictions to your experience as you approach the end of Hogwarts Legacy. However, if you need more convincing, it's important to dive into Sebastian's story and why he ends up in trouble.
If you chose to 'open it', embracing the 'evil' ending, Professor Fig will be killed by the Ranrok Dragon in the cut-scene before the fight. This is a blink-and-you'll-miss-it moment, with a massive pile of debris being walloped onto your kindly mentor.
I have chosen to lecture on Voldemort's mother, Merope Gaunt, because she is an example of that type of secondary character who seems very minor but whose actions are indispensable for a story to start moving. If poor Merope had not fallen in love with the Muggle Tom Riddle, Lord Voldemort would have never been born.
He hexed or jinxed Tom Riddle Snr (a Muggle who lived near his home in Little Hangleton) with painful hives because his sister was infatuated with him. After this attack, his recklessness and disregard for wizarding law attracted the attention of Ministry of Magic officials, who sent Bob Ogden to speak with him.
Are all parselmouths descendants of Salazar Slytherin?
Not counting Herpo the Foul, who predated him by several centuries, nearly all known Parselmouths were descended from Salazar Slytherin, with Harry Potter being a notable exception (although he gained his ability as a Parselmouth in an unorthodox manner).
