Unless you are a hardcore one trick who will not play anyone besides your main like Tyler1 chances are you will play against your main from time to time. With my main being 
if they are actually good with him I absolutely hate it but if they aren't then I love it cause a bad Thresh does nothing and they are just free gold.
Yes. Both 
and 
are cancer to fight when they are really good.
i ahte it because i'm afraid they will play better than me and it will not pleasant :3
I never vs my main because I am a Skarner Top main. I have yet to see it.
Depends on who I'm playing. The other day, for example, I played a game as Caitlyn vs Twitch, who is the best ADC in the game right now and has been my main for a while. On the one hand, maining a champion means you know how to play against them pretty well, but on the other, when you're on a champion who you don't know how to play very well in the first place (I've only played like 3 games as Cait), it's not very fun because they likely will poop on you. However, you can learn from that game as for how to play against the champion you played as your main if you get pooped on by watching what the enemy does to poop on you. Hope that makes sense. It's midnight, I'm kinda in random ramble mode.
idk. everytime I see riven picked I just go vayne. and then they rage quit.
I hate playing against my mains, because it makes me cri every time when i kill them ;-;
R.I.P. 
I always go against my mains...... im a support main. the only supports im not at minimal good with is taric, zyra, and alistar. Even then i can pass as atleast mediocre normally lol (not bragging, i know theres people that are better, but they are good as well, better than i am, which is fine :P)
I don't really have a main, but Poppy is one of my favorite champs. I feel bad for killing her. xD
I love it, because then I know my opponents ins and outs. Possible killing potential, cooldowns, trading power...
Also, my second main counters my main.
