Schizophrenics, like most other people with mental disorders, aren't a whole lot more dangerous than a regular person. Considering it sounds like H has had his schizophrenia for a while now and is receiving treatment I would say the chances of him doing anything are extremely low. Even if he does do something it's probably going to be more along the line of him showing up at your house at 4:00 AM babbling about you stealing A and cursing at you than him axe murdering you.

Do be on alert if he goes off his meds or stops seeing his therapists since that will most likely be the time he'll do something. At some point in the future he WILL go through a period where it gets worse and his hallucinations, delusions, ect, will increase, which will also be a time when he might do something, but it will pass with time and he'll get better again. It's a cyclic thing.

Also, keep talking with H and encourage A to keep talking to him too. Schizophrenics are usually lonely and having someone to talk to is good for them and their treatment.