Ohohohohoo you are in for a good one. Laxus would either be super clingy and constantly ask for your attention by following you around, giving you secrets hints or literally whisking you away to spend a day with you at home to cuddle... if he is THAT needy.
A phase before that one may be, Laxus tries to hide his neediness and pretends like he is fine and 'a strong man' who doesn't 'need' attention but anything you give him is 'a bonus'. Of course you see his actions that clearly indicate he craves to spend some private time just the two of you, either on a date or alone because he misses you and wants to have you only for yourself at that time. Give him sum love pls, our thunder pikachu needs some attention <3