Hello there! Glad to see your tastes are varied (and good).

I'll try and narrow things down based on universe:

Marvel / X Men:

Tony x Pepper doubling with Steve x Natasha (while I love the pairs, the plot must be solid enough to sell me, I've had too many wonderful stories fade away due to ill fitting partners)

Megneto x Mystique doubling with Professor X x Pepper (it could be interesting)

Star Lord x either Pepper or Mystique (either way, I could try either Star Lord or the other female, possibly other Guardians if needed)

Yu Yu Hakusho:

Yusuke x Young Genkai or Botan

Kurama x Botan

Harry Potter:

Draco x Luna