Unfortunately, bot lane requires on synergy and it's just sometimes not there. You can do some little things though.
If your lane buddy is too aggro:
- Ping your summoner CD (Heal in particular). Some people still don't pay attention to this and play as if you always have summs up 24/7. Pinging stuff like mana % and ult timer is pretty useful as well.
- Tell them to play safer if they keep getting caught. "Stay behind minion line if you can," is usually a good way to start if they keep getting hooked.
- Ping them back. Tell them you just want to farm if you don't want to all in.
- A bit off topic, but whenever you see the jungler anywhere else on the map (i.e. their jungle or roaming river) ping their location. That way, you might be able to improve your support buddy's map vision if they themselves didn't see the jungler and maybe they won't try to engage too hard.
If they're too passive:
- Basically just CS as best you can. Use the blue ping if you want to all in. There are certain people who will follow up, and if they don't, just keep that in mind next time you want to initiate a fight.
- Poke when you can, but if your partner's too passive, keep in mind that poke =/= trying to kill. Just whittle them down and make the enemy duo not want to all in.
The on-going Relic Shield issue:
- Ping things like Cannon Minions and Melee Minions so that your support knows that it's okay for them to go for it
- If you notice them missing a lot, just try to CS as usual. If you get they get the execution off, cool. If not, you get the CS anyway.
tl;dr use pings if you don't wanna type stuff out. It's generally easier and besides, Riot's finally added ways for us to ping CDs. Just don't overdo it, one or two is fine. Good luck on the Rift.