To the question "What compensation should the recruiter get when I terminate my contract", the answer is none whatsoever.
His or her job is to find companies wanting to employ contractors, find people who want to work as contractors, put them together, and if that works and the company stays together with the contractor for a long enough time, then he or she gets paid. Since he didn't deliver what he was supposed to deliver (an employee who starts and stays long enough), he didn't get and didn't deserve any money.
What he is doing is like you going to a car dealer, looking at all the cars, deciding that you don't want to buy one, and then the car dealer tries to charge you for his loss if income because you didn't buy one of his cars. It's ridiculous.
If he refuses to pay you, first you need to check your contract with him. Hopefully it doesn't mention any reduced payment if you leave. Whether it does or not, I'd send a registered letter demanding payment within 14 days or otherwise you will have to take appropriate legal steps, and I'd send a copy of the letter to the people you were working for. I bet they paid full price for your work, and they won't be happy to hear something like this.
Saying that you are in Germany, this makes it most likely that he would have to pay all your cost if you take it to court and win.