The Climactic Final Battle of Disk 2. You might remember in the canon Seifer has a little unique thing he says to each party member.

Well...

Seifer leads the party to confront Edea and Evi!Squall.

Squall to Zell: ...
Zquall to Selphie: ...
Squall to Quistis: ...
Squall to Irvine: ...
Aquall to Rinoa: ...
Squall to Seifer: ...whatever.

Also End of Disk 3 Spoilers.

Seifer: So you're Squall's dad.
Laguna: Yeah but don't tell anyone. Kinda awkward with my son being oN Galbadia's side and all. I was thinking maybe you guys could try to like, redeem him or something.
Seifer: I'm gonna stab him in the face. Does that work?