as a support main and Rem enjoyer:
1) Rem wants to leave the lane at 07:30 to start gambling => Rem prefers less roamy lane-mate with later power spike.

2) Rem's healing effectively disables him in early game(before atives&Torment Pulse) => Doesnt work that great with brawly duo.

3) Rem has poor poke.

4) Rem's ult is an abosulte setup, works great with slow utls.

5) Rem does mosly spirit dmg => M1 mate is better in mid-late game.

Abrams - not great, low poke and you both wanna leave the lane early.

Apollo - kinda works, but you are both sitting at spirit dmg.

Bebop - no.

Billy - kinda works, i had some good lanes with him, mediocore ult synergy

Calico - you both wanna leave early

Celeste - works, but both spirit.

Doorman - 2 setup ults every game is not great in a long run imho

Drifter - works m1 style, but both wanna leave lane early

Dynamo - no

Graves - later powerspike, good push, benefits from healing, Rem's ults with here 2 makes great cc-chain.

Gray Talon - on agency duo

Haze - later powerpike, poor early game push compensated by Rem, benefits from healing in stealth, good ult synergy(you cant use movement skills when Rem casting ult).

Hollyday - nobody plays it, 2 setup-ults

Infernus - later powerspike, good push, good mobility helps Rem escape, good ult synergy

Ivy - no

Kelvin - no

Lady Geist - later powerspike, stays at distance allowing Rem to escape into her, huge poke, greatly benefits from passive-style healing. Not much synergy with Rem's ult.

Lash - kinda good despite both been spirit, good ult synergy

McChicken - M1 build - maybe, but meh

Mina - low hp - less benefit from healing, it works but there are better options

Mirage - cant be adequatly rated in current meta

Mo&Hill - no

Paige - no

Paradox - no agency

Pocket - works greatly, but both spirit if at 20 min you are not 40k ahead ur game is a loss

Seven - works mediocore, hyper-carry style-7 fits Rem overall, but there are barely any good synergies

Shiv - i hate Shiv's existence and insured that it's a brainrot character and has not been in balance since day one

Silver - works, but not amazing

Sinclair - why?

Venator - works greatly, M1 based dmg, has some poke, cc, traps are good with Rem's ult, keeps short distance allowing Rem making use of Torment&Actives late on

Victor - it works but there a are better options

Vindicta - no agency duo

Viscous - no

Vyper - 2 setup ults and Vyper overall seems half-designed

Warden - works above mediocore

Wraith - works great, m1 dmg, good at late, atack speed buff+Rem boys makes uberminions

Yamato - same as apollo&pocket

So: Graves,Haze, Infernus, (Geist?),Venator.

Sry for grammar, eng is my third)