Name_Unknown
He can join Vali Lucifer and have fights with strong beings, nor that being with Rias Gremori will always give him fights, rather it will only bring him problems, and worse for being the last of his race, he will see himself being harassed to join the nobility of any interested party, instead with "vali lucifer", you can have all the fun you are looking for, I don't know why the authors always think it is good to go with rias gremori xD.
Name_Unknown:He's really not strong enough to knock around with Vali and his group. He'd get squashed by one attack from anyone in that group at the moment. Being around Rias and her peerage brings fights. Problems? Yeah, problems for people who are weak-willed, like yourself, but something of interest for anyone with even a semblance of courage or a brain cell lol.
I have some ideas i like to share with author. You see in avery inhalation and exhalation there is a point where we wan't inhale or exhale where we go comple stillnnes to go this stage one had to medating and controlling our breath to go complete stillness again of few second.in this stage our body automatly recycle our system.it will strength host spirt,heal all hidden wounds and remove all harmfull substances.