For me all the main 6 characters: (Tyrion,Sansa,Daenerys,Jon,Arya,Bran)
go through a change in their personality. In different circumstances, of course.
I would separate them in three groups: Tyrion and Sansa (both create an alias, a bastard, so they cannot be found by Cersei, and they learn from it, they use their wits to create that personality), but they never forget their old selves (and I believe, both will refuse this “lie“ in the future of the story).
Tyrion took a mordant pleasure in inventing the details of the colorful life of Hugor Hill, also known as Yollo, a bastard out of Lannisport.The best lies are seasoned with a bit of truth. The dwarf knew he sounded like a westerman, and a highborn westerman at that, so Hugor must needs be some lordling’s by-blow. Born in Lannisport because he knew that city better than Oldtown or King’s Landing, and cities were where most dwarfs ended up, even those whelped by Goodwife Bumpkin in the turnip patch.”- Tyrion ADWD
Music soothes him,“ she corrected, "the high harp especially. It’s singing he can’t abide, since Marillion killed his mother.” Alayne had told the lie so many times that she remembered it that way more oft than not; the other seemed no more than a bad dream that sometimes troubled her sleep. “Lord Nestor will have no singers at the feast, only flutes and fiddles for the dancing.” What would she do when the music began to play? It was a vexing question, to which her heart and head gave different answers. Sansa loved to dance, but Alayne . . - (Alayne/Sansa) TWOW.
Then there are Jon and Dany both messiah figures, both literally die and becoming stronger version of themselves:
“Viserys was Mad Aerys’s son, just so. Daenerys … Daenerys is quite different.” He popped a roasted lark into his mouth and crunched it noisily, bones and all. “The frightened child who sheltered in my manse died on the Dothraki sea, and was reborn in blood and fire.” - Tyrion in ADWD
“Kill the boy and let the man be born.” The old man felt Jon’s face. “You are half the age that Egg was, and your own burden is a crueler one, I fear. You will have little joy of your command, but I think you have the strength in you to do the things that must be done. Kill the boy, Jon Snow. Winter is almost upon us. Kill the boy and let the man be born.” - Jon ADWD
There are then Bran and Arya whose alteregos are connected with gods (the old gods and the
respectively), both are like a “weapon” being trained by the tree eyed raven and the faceless men for a scope (also both i believe will reject this notion and return to their Stark identity)
I should not be dreaming wolf dreams, the girl told herself. I am a cat now, not a wolf. I am Cat of the Canals. The wolf dreams belonged to Arya of House Stark. Try as she might, though, she could not rid herself of Arya. It made no difference whether she slept beneath the temple or in the little room beneath the eaves with Brusco’s daughters, the wolf dreams still haunted her by night … -Arya AFFC
Leaf touched his hand. “The trees will teach you. The trees remember.” He raised a hand, and the other singers began to move about the cavern, extinguishing the torches one by one. The darkness thickened and crept toward them.“Close your eyes,” said the three-eyedcrow. “Slip your skin, as you do when you join with Summer. But this time, go into the roots instead. Follow them up through the earth, to the trees upon the hill, and tell me what you see."Bran closed his eyes and slipped free of his skin. Into the roots, he thought. Into the weirwood. Become the tree. For an instant he could see the cavern in its black mantle, could hear the river rushing by below.
. - Bran ADWD