Cosmic Ghost Rider: Thanos of all people, by the Cosmic Ghost Rider. The Rider raised Frank after not being able to follow through with his plan of killing baby Thanos in his sleep, and while turned out much worse for his new upbringing, he shows nothing but love and respect for his adoptive father.
Deadpool: Deadpool's daughter Ellie is this. For the first 8 or so years of her life, she was living with her foster father, the brother of Deadpool's worst enemy. She loved him dearly and was heartbroken when he was killed. When Deadpool came to save her, it's revealed to her that she's his daughter. After Deadpool fights off all the enemies and scares Flagsmasher away from his daughter, he asks his friend, S.H.I.E.L.D. agent Emily Preston, to take his daughter in and raise her for the time being. Later when Deadpool is visiting her, he asks if she's happy. Ellie says that the Prestons are cool, and Deadpool is glad because she's safe with them.
Recent chapters show Ellie would rather be with the Prestons than with Deadpool. He takes her away from them, to protect her. She yells that she doesn't want to go. At one point, he picks her up to carry her away and she yells for him to let go. While living with him, he comments that she wants to go back to the Prestons and cries.
Runaways: The Runaways are one big happy adoptive family, albeit one whose adoptions are not initially legally recognized. Attempts to break them up and send them to different foster homes have never worked out, and have sometimes led to fighting. However, when the team took Molly away from her evil grandma, they realized that if they wanted to send her back to school (which she loves), then there has to be a legal guardian of some sort. What to do? Nico took her magic staff and said "Legal adoption", and that was it. Nico and Chase are now the legal guardians of Molly.
This turns out to have been the fate of Klara after the group split up; since she didn't have the accidental death of a parent or a long history of breaking out of foster care on her record, she got taken in by a nice gay couple and has thus declined to go back to being a Runaway.
Peter Parker's parents died years ago, so he was adopted by his aunt and uncle, Ben and May; and then just May when a burglar killed Ben. He is happy and fine with May. May is happy with Peter, too, but she is greatly troubled by the memory of all those people she has lost. So she also adopted Gwen Stacy (a teenager whose father was killed and her mother run away). And, after the worldwide disaster of Ultimatum, she also allowed Johnny Storm and Bobby Drake to stay in the house. And add Mary Jane, who was not legally part of the family but spent a lot of time with Peter anyway, and you get a full house.
Jimmy Hudson was conceived by Wolverine and Magda, but Wolverine gave him to the Hudson family. He thought that, if he took him, he could either be a victim of some villain, or turn out just like him. As seen in the Ultimate Wolverine miniseries, Jimmy thinks that Wolverine is his biological dad, but his adjectiveless dad is James Hudson.
Cable is the son of Cyclops and Madelyne Pryor, but nonetheless considers his real mother to be Jean Grey, since she's married to his father and was the woman who raised him. She also technically counts as his biological mother, since Maddie was a clone of Jean.
Jean Grey also has Nate Grey, Cable's alternate (and half-brother, since he was created from Jean and Scott's DNA) from the Age of Apocalypse. So, Jean is technically his biological mother, but also the alternate counterpart of his biological mother. Despite this, and the fact that Nate's relationship with the X-Men is often difficult and strained at best, he has always—always—treated her as his mother, and she has treated him as her son. She's also just about the only person he's consistently listened to: Mystique in disguise as Jean is able to talk him down from frying Dark Beast during Dark Reign (finding out she was dead left him very, very angry) and she convinced him to briefly join the X-Men. His failed attempt to give her the Glorified Sperm Donor line in Uncanny X-Men (2018) was the first sign that he wasn't so detached as he was pretending to be, and shortly after, he revealed his attempt to unite and forcibly fix the world was done as part of him trying to make her proud.
Subverted, but also played surprisingly straight with Rogue's adoptive parents Mystique and Destiny. By all evidence, Rogue had a happy childhood with them, which is all the more surprising considering the kind of mother Mystique has been to her biological children Nightcrawler and Graydon Creed and that Rogue was raised to become a member of the Brotherhood of Evil Mutants. Still, Mystique and Destiny must have taught Rogue to think for herself and respected her choice to reform and join the X-Men even though that brought a painful separation. Rogue continued to feel an emotional attachment to her adoptive parents that lasted until Destiny's death (and beyond, vide her brief resurrection in Necrosha), and if she eventually fell out with Mystique, it was because of horrific acts Mystique perpetrated after the separation, not because of a reassessment of her upbringing. By the time of Rogue's wedding (in 2018), she still loves Mystique enough to address her as "Mom" and let her watch the wedding from a distance.
Wolverine and X-23 are both quite aware that she's his clone (sort of), and he has no real obligation to do anything for her. He adopted her anyway, and the relationship is about as happy as Laura gets. His Relationship with his son Daken...Isn't as healthy.'
Young Avengers: Wiccan and Speed are adopted by Muggle Foster Parents, but still love them even after discovering their heritage. Sort of. It's complicated.
