What should I do in this situation where I like my brothers friend?

I'm 21 and my brother and his friends are 23. About a month ago, I went to a party and the 5 I know (my brothers friends) were there and they seemed really happy to see me, I noticed a few were clearly showing of. One in particular (the one I mentioned that I’ve always felt we might even have something). When he first saw me, he came over and gave me a hug and while we were standing in one room, I could see him trying to look at me but at the same time hide it. Then he jokingly I think (as he definitely would know I'm older than 18) asked me to come out the back with the mates and my brother to play beer pong, he said something along the lines "Come outside, are you even 18 yet?" with a smirk. For most of the night was leaning against me, standing incredibly close, putting his arms around me, talking to me, showing of that he was an Iron man champion which is true. Talking about his job, what his sister does as well since I mentioned I work in dentistry. He then of course showed of his pearly white beautiful teeth and told me how perfect they looked compared to his twin brother. Showing off again. He was speaking to me about a ray of things such as how racist the work force can be to non white individuals, since he’s the typical tall blonde like me. I vaguely remember us joking about a lot of things. We spoke probably for hours. They were playing beer pong so obviously they were acting like show ponys, most of them but this one in particular.

When I told him that I used to have a boyfriend as it somehow came up in conversation, he clearly seemed to have an issue with it. Sort of made fun of the guy that I used to be in a relationship with. One point his friend picked me up to get something of the roof. We continued to speak through the night and then I went to use the bathroom and came out and they were just about to leave, he was looking at me while I walked out of the bathroom with a slight look as if to imply he was leaving.He told me at the end that if I get bored of my boyfriend, to message him. Which was a sign to me he's interested but also a bit weird since I'm not even with the guy anymore. He then added me on FB after. We do not see each other that often but when we do, I do feel there is some sort of tension. The next day or so my brother was telling me the guys was messaging him saying it was so funny how I just threw the ball into the cup when we were playing beer pong instead of bouncing it.
There could be uncertainty also since he’s my brothers friend.

Recently I added him on Instagram and he followed me back but that is all.

The other day my brother had his birthday party and this guy walked in and clearly looked nervous, said hi to some people and then didn’t exactly come over to me but just mumbled saying hi to me with my name. I could tell he was looking at me throughout the day. Standing next to a few of his friends while I was nearby and somewhat showing off. I was sitting at a table and he came over and just sat in front of me but didn’t make that much conversation. I could tell he wanted to but just didn’t. Then my brother opened a present, he was sitting in front of me and I could tell he was looking at me while I was looking at the present. Where do I go? I could tell he was nervous the other day.