Why do I find this Gemini so annoying?

I went to high school with this guy, he made me laugh a few times and things were fine. He ended up dating my Capricorn friend a while back basically guilt tripping her into by saying she always friend zones him and it's not fair and he loved her so much or whatever. The relationship barely lasted a week and he ended up breaking up with her saying he needed to figure his life out. She was pretty annoyed and I said it??d be best to just forget about him. Later on he got back into her life, they text every day and recently I was with my friend and he visited us. We all sat and talked, and I noticed some things about him??_
1. He always tries to be funny around people, like he's desperately trying to make everyone laugh
2. He's really destructive to himself. He drinks excessively, smokes nonstop, and always makes light of his harmful actions.
3. He's very clingy and dramatic??_I don't want to say expressing your feelings is a bad thing, but the way he does it and the timing is always so strange??_he texts my friend saying he loves her and would never hurt her??_but HE DUMPED HER when they dated??_.
As of now my friend is torn, not knowing whether she should give him a chance or not??_.he seems to be way more emotionally invested in her than she is in him. I suppose I'm wondering if these are normal Gemini traits or should I look at his chart? From what I??ve heard Geminis and Capricorns don't click??_.
(also I'm not saying I dislike all Geminis. I have 3 Geminis in my life that are awesome I just have some issues with this guy)

I totally get what you mean by annoying gemini! I knew this gemini friend who's totally a drama king like that guy, but he had his other downs too like he was super cheap and always like always borrows stuff, cigarettes, food, tomatoes anything! he was also really disgusting like he farted in front of friends and all! he used to be really smart and very sweet but suddenly in a few months time he became this pest... anyway for the romance part he's been dating a girl for very long time and there was this new girl and he dumped his girlfriend for this girl and now these two are together for more than a year, I think its just how they are! you can ask her to totally ignore the guy and then maybe he'll be back begging her cause one thing I know they LOVE attention.