Ok guys so I need some help on something. Every week starting this last month me and my 2 guy friends go over to another friends house. The guy has a sister and she is HB9 for sure and she always invites the same friend over who is about the same. But anways I know this guys sister finds me attractive because she is constantly giving me the stare downs and getting close to me and what not. But anways recently I have decided that when ever she gives me the terror stare down I would lock my gaze with her and see who could stare each other down before the other person submits. Last time I was over we had 2 to 3 big stare downs where I will catch her staring at me and instead of looking away I would stare back. Now these stare downs are lasting 5 to 6 seconds and the last couple of times we were looking at each other she turned the gaze and put her head down but then I would catch her staring again and it would happen all over. And these things are in intense man, they seem like a game but are also kinda sexual. I'm trying to figure out what this means when she stares u down and u do the same and she submits, but they last Forever,
Some in sight about what going on/how to escalate this would be great.

If you don't make a move quickly, this will just turn into a friendly game that you two do with zero sexual tension. Do a smirk or something, but make a move. She's giving you IOIs and you need to take it.

I agree, I would make sure theres gazes remain sexual then start to escalate from there. Like ^^ said give a little smirk next time, then after that you could sit beside her, maybe touch her arm, then her hair. This will also let you know if shes interested or not just make sure to do it smoothly. Goodluck

You have the attraction, now you need to build some comfort, just go over and make a bit of conversation, ask her questions, find out things about her, but don't rush it, make it so you are both comfortable talking with each other, when you have comfort, hit on her, make sexual advances, if she resists pull away and try again later, or another day, assuming you are still getting ioi's.