Rick Jones, friend of all superheroes and your neighborhood sidekick. Very human and very super-powerless (mostly).
Captain Marvel, tube son of a legendary hero with the same name, alien, half-breed, Kree. They really don't share any bromance the like Spock would usually require to at least consider cosplaying. But he might've been won by the way one is related to the other.
During a very complicate, all-continuum threatening war, Rick has taken a fatal energy blow. A Captain Marvel, coming from the future and who has tried all the time to change to especially avoid this from happen, has to again share his life-force with Rick to save him. They become like one, sharing molecules: when one is on Earth the other is in the Negative Zone, when in front of any mirroring surface they see the other's reflection, they speak in a way that could resemble telepathy; both with a life of their own (well, fine, Genis doesn’t really have a life, besides booze and women), but completely dependant from each other.
One a part of the other, in the most physical meaning of the word. They share so much, and in such an intimate way, that they piqued Spock's curiosity. They just have what he would mostly want to share with Jim - though the downside would be no more sex, and Spock doesn't really agree with the idea to stop taking his delicious nepik ("submissive") let alone not be able to live on the same physical plane at the same time.
Let's just say that this couple-not-couple was Spock's pick. Jim wasn't this happy, considering all it took him to dress as Rick was to procure a pair of gold bands and snag something casual from his closet while his hubby had all the fun with the costume, the wig and the bodypainting. He may have pouted some hour because of this, even because he likes Genis more but Spock's been adamant: the stronger (and the alien) of the two was going to be him.