Hi there,
I can only speak from my personal experience as a (possibly, not tested but matched all the characteristics) gifted and sensitive person who dealt with father abandonment issues. I've also had plenty of experience watching friends deal with similar situations.

[Note: I'm not a therapist and it sounds like getting a professional opinion on this might be a good idea. I'll just share my thoughts and hopefully they will be of some help to you!]

From my personal experience, the reunion with the absent parent can be very difficult, especially for sensitive souls, that truly want to embrace their formerly absent "parent" and make them feel loved (even if perhaps they don't deserve the loyalty.) I think many sensitive children will take on the guilt or responsibility, not even realising that they are blaming themselves for the parent leaving. There is the sense that "I must have been bad" for them to want to leave. This is completely illogical to our reasonable mind but sensitive people often work from that intuitive, feeling place and will apologize for others behaviors and take on the pain and guilt themselves. It took me many years to realise that I'm not at fault, he had to leave for his own reasons and that now that he's back in my life (he returned when I was 12, I'm now 36) it's ok to go slow in getting to know him, it's ok not to trust him and to not feel like I have to apologize. Yikes! There's quite a bit of "stuff" in that.

BTW, in my particular case my dad left for draft resistance reasons and is a kind soul that just wanted to reconnect with only an emotional agenda, although he continues to be a hermit and we speak infrequently. As an adult, and now a parent myself, I've learned to accept what he brings to our relationship without expectation. We have connected occasionally and have a very caring friendship. It took a long time to get to this place.

I agree that you should be VERY cautious. I agree that you should be very concerned about his agenda and his ability to respect your boundries and your sons emotional, mental, and physical needs. I'd think that before you even allow him to be involved, or see your son, there should be serious trust building between the two of you and some real concrete proof (time, writing, financial, whatever) that he is committed to all of your conditions. In my opinion he has forfeited all his rights and you have control over the situation as the protector of your sons best interest. Also, it may be very troubling to your son if he is back and then flakes out again.

Sorry you are struggling with this. It's never easy and especially when dealing with someone who is unreliable and difficult. Please feel free to email me off board if you want to chat more.

Best wishes,
WW