well, to be fair, ed said he can fuck chang and not that chang can fuck ed. and he was quite clear when he said stop, when he punched him, when he was trying to get away. if that's not a clue to stop then I don't know what is. Also chang is not some random dangerous gangster but someone ed knows for ages, he thinks he's someone who's a homophobe so why would he be interested in having sex with him?
Ed said later, I changed my mind, he tried to protect himself, tried to get away but was clearly forced down. So it was clearly rape. And other people's ocupation doesn't justify the act of rape. It wasn't a case I wanted to have sex but after it I regret it so i'll tell everyone it was rape. yeah, he teased him but if he was willing to do it with him it was on different grounds. And then his opinion was completely ignored. rape.
Ed played the game of holding one's hand over a fire. At one point, your brain sends signals of pain to let you know you're burning your hand and you need to pull it away from the fire before any major damage is done. Ed not only ignored that, but gleefully pushed his hand directly into the flames to show off how tough he was. He's perfectly aware of what fire is and what it can do. Of course he got burned.
Which would be a valid point IF Chang wasn't a criminal. Which Ed is completely aware of. It doesn't matter how long they've known each other - just look at how he's fucking him (heh) with the vast sum of debt. Ed knows he is scum.
Would one provoke a gangster in real life and expect to walk away unscathed? Obviously not. He was poking a tiger and got bitten.
He did provoke a guy he KNOWS IS A DANGEROUS GANGSTER. Dude, why didn't you leave instead of taunting him saying you would fuck him?
Grow up, that was never going to end well Σ(  ̄□ ̄||)