If Gellert knocks over the potions shelf and shrinks to the age of 11 and receives a letter of admission to Hogwarts, he enrolls in the same year as Harry Potter and becomes friends. He and Albus will only have this chance to come back.
Albus: Why are you here?
Gellert: Al, you are here, and I am following in your footsteps.
Albus: So how did you get into Gryffindor?
Garrett: Because you graduated from this academy!
Motto: Everything has a chance to come back