Age gap

Uke a lot older (at least 10 years). Uke meets seme when he's a child in a forced marriage, they are soon separated and reunite when he's 18.

Seme over 10 years senior

Seme like 10 years older

Uke is 8 years older, bit also stuck in a 16-17 state, so now he's 26 and seme 18.

MC probably 20s and ml is 41

Vamp and were

23, 30+?

21, 36 (+18)