I think that it'd be cool to host a symbiote coupled with the ability to absorb other's powers like Rogue. That seems pretty boss--and pretty strong. The lonliness Rogue feels being physically isolated from humanity would be alleviated by the strength of the symbiotic bond. You wouldn't need anyone else.
Silver Surfer and Superman: Super Surfer
Green Goblin and Scarecrow: Fear
Hawkeye and Green Arrow: Quill
Darkseid and Galactus: Galactuseid
Clayface and Sandman: Mudd
Dr. Strange and Ra's Al Ghul: Dr. Al Ghul (yeah i know its lame)
Nightwing and Daredevil: Nightdevil
Magneto and Martain Manhunter: Mutant Manhunter
Batman and The Punisher: Frank Wayne a.k.a. Vengeance
they might be lame...or their names might be taken...but either way they are some cool ideas (i think)
Bat-Venom? I don't know, shitty name, but whatever.
Edward Wayne (or Bruce Brock, whichever you prefer) witnesses his parents murdered before him. He goes into journalism, seeing it as an oppurtunity to help dredge up facts and solve cases that don't get solved (need to work that out, because if he wants to do that why doesn't he just join the police force? New Gotham Frisco is some sort of dystopian city and the Police don't do anything) while also embarking upon a small nighttime vigilante career. Using mommy and daddy's fortune he becomes a tycoon and finances a newspaper. Spider-Boy does something to ruin his career as a journalist, and the sting hurts doubly because it also got his nighttime vigilante persona in deep water. He goes off the deep end and falls into a vat of cream of wheat (thank you Everett K. Ross) while praying in an abandoned chapel. The tasty breakfast food reacts to his hatred and bonds with him, creating a Bat themed symbiote, because of some spooky Bat-themed foreshadowing he noticed in the artwork. He's very heroic, with some psycho tendencies, and he has a huge mad-on for Spider-Boy.
The Cream of Wheat thing came from a Black Panther comic. Panther's U.S. ambassador/liason guy, Everett K. Ross would file reports on his encounters with BP, most of these led into various super-battles. He would always give a run down on the various super types involved, after awhile he got tired of explaining their origins. Falling into a vat of cream of wheat soon became every Marvel hero's origin story, because Ross was tired of the paper work.
The Doctor Strange and Ra's Al Ghul thing has promise, I think. Although it should be something 60's and campy like, Proffesor Ghoul. or Ghoul, Md. Having Ghoul as his proffesional spandex pajamas name would fit because people would think of ghosts and stuff, which goes with the supernatural, which in turn fits with an incredibly long lived sorcerer supreme.
Silver Surfer and Superman - Silver Man (cheesy? yea)
Man i wouldnt wanna mess with this guy. Adding their strength together making them possibly the strongest being in creation. SS's almost indestructable skin and SM' invulnaribility(sp) making him almost very nearly immortal in a way. The ability to control the power cosmic, Heat vision, hyper flight and normal, being able to move at speeds reaching that of light, very cool costume and surf board might i add and all the other minor stuff Superman and Silversurfer can do. Very powerful character. ✅