Why is rammus twitches rival?

If they were friends I would say it's a reference to TMNT, but I have no idea

And they would both be rivals to Zed.

Rammus lore is extremely vague too. It is just riot asking me questions about him, like I know the answers.

His smell its not ok

{quoted}

Also where does twitch even come from. His lore is so vague.

Twitch is from the sewers of Zaun.

Rammus hates Twitch because Rammus' girlfriend, a cactus, cheated on him with Twitch.