First of all I'd like to thank you for coming to my fanfic of LoudFortress. Anyways here's the casts:

Undertale ones(They're gonna be part of the story too as supporting characters):

Papyrus as President Papyrus

Sans as Sans

Loud house ones:

Lincoln as Lincoln

Lori as Lori

Leni as Leni(Scout's wife)

Luna as Luna

Luan as Luan

Lynn as Lynn

Lucy as Lucy

Lana as Lana

Lola as Lola

Lisa as Lisa

Lily as Lily

Team Fortress 2 ones:

Pyro as Pyro

Engineer as Engineer

Spy as Spy

Heavy as Heavy

Sniper as Sniper

Scout as Scout(Leni's husband)

Soldier as Soldier

Demoman as Demoman

Medic as Medic

Yep! Scout and Leni are married now. I'll explain it on the other chapter.