I had a "runaway buddy" once, out at Stetson Bank near the Flower Gardens..
I should have known better, she was a headstrong and difficult personality on the boat, had to sit out a dive after going deeper than the boat allowed. But my regular buddy was going to sit it out, this was the last dive before the boat would head for shore. So I buddied with her, for "just one" dive--what could go wrong?? Really dumb question as it turned out.
She was definitely not much of a buddy, went wherever she wanted almost never checked in with me about air remaining, where to go, when to turn the dive, the basic stuff. It was like "herding cats", but I finally cajoled her back to the anchor line, I was down to 700. I turned my SPG towards her and tapped on it, I wanted to know if she had enough air to make a normal ascent, we were at about 80 feet. Nothing. Then she let go the line, and took off heading "aft", but not near the boat, towards some distant pinnacles and disappeared behind them, far away and almost beyond my distance of visibility,
Aw, Crap. Do i go after her? No, I can't, not enough air left for an uncertain-distance chase, where is she/ can I even get her to stop and ascend-type scenario. So I didn't chase her. And started ascent, all the while wondering where she was, was she out of air, am I a "bad" buddy for not chasing, what if she dies, is it my fault? Damn. Why'd she put me in this position? Is she all right? Why me, God?
Well, and fortunately, a happy ending--evidently some time after disappearing, she went to the stern, and ascended straight up without a safety stop. She was casually chatting with a couple of the very few people still speaking to her...I never did find out how much air she had left.
Not long after, I went to the DM and the Captain, told them what happened, I wanted to know if I'd done wrong, or right. They told me I did the right thing, better one casualty than two. I still would've felt guilty if she had died or got bent, even though there was nothing I could have realistically done