One of my friend's bike got stolen, and who must repay it?

[olivermag]

Ok, I am having a small problem here. One of my friend's bike got stolen, but the scenario is really particular. So this friend of mine (Gab) went with his bike to one of my other friend (Remi). He slept over there. The next day, his mom came to get him by car, so he left his bike at Remi's house. Remi doesn't have a bike, and he needed to come over at my house, so he took Gab's bike. We needed to get somewhere far, so we used my car. So, Remi left Gab's bike in my garage. Two weeks later (yesterday) I used this bike to go at Tim Horton's (some coffee shop). I left the bike outside and it got stolen. This was a pretty valuable bike. I think it was a GIANT that cost Gab like 600$. Now, we must decide on how we pay the bike. Gab shoudln't have left the gab at remi's place, Remi shoudln't have left his bike at my place, and I shoudln't have left the bike at tim horton's. Remi says that it's gab's fault that he left his bike at a friend's house. Though I'm not sure, any advice?