Taking out previous loans for smaller amounts doesn't in any way guarantee that you will pay a larger amount back. This could just be a classic long con. If you've already got 1btc loaned out from Marco then that is also worrying and I agree with QS that it's weird you would get such a loan in the first place without any collateral (though I'm sure he could just take it out of your signature earnings). I'm really not sure if MZ or Marco would vouch for this other than that you paid their previous small loans back.
Marco did try to vouch for him last night (I was proactively contacted about the OP by Marco). I haven't been able to verify the loan from MZ although I haven't looked into it.
One other thing I forgot to mention, the OP claims to have 4 hero accounts, also didn't try to look into it as 4 hero accounts are worth <2
BTC.