Just be there for him.
Bottom line is if there is any kind of abuse - mental, physical, sexual - for a start he needs someone to trust. Don't worry about the words he uses - calling you dad or I love you. If he plays with you, that has to be good enough for now.
If autism is part of the issue, that might make some sense depending on how old he is for some of the issues.
Crying and sensitivity - depends, I know my daughter is VERY empathetic - she can cry over mom leaving the house - at 7 yrs old! She get's it under control quickly, so it's ok.
Autistic kids are often very sensitive to change - sounds like there might be a lot of that - people who are/have watched him, boyfriend / dad -- arguments. Actually, ANY kid would do well with a normal consistent routine, but if you think there is autism, it is very important. Simple things like dinner time, then tub time, story time, then bed time. Consistent EVERY night.
Again, In my 'non-expert' opinion, I would focus on just being a positive person in his life. Try to get along with everyone else - the dad for example - if you are this person, he will naturally get closer to you. Then just keep an eye on behavior - don't try to question him, just see how he acts after spending time with dad, grandpa, etc. Look for patterns.
Oh, and if there is autism, often play time is a little different -- you have to learn to be OK with that -- you might not be able to play catch -- you might have to play imaginary pirate or dragons and knights.
Hope that helps.
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AAIG
