Turns out one of the Holmes boys is not actually a Holmes. Mycroft drops all protection/guards/'sponsorship' to Sherlock because he (either Mycroft or Sherlock) are no longer related in a brotherly way.
Expansion or prompt: Basically, somehow Sherlock and Mycroft discover that one of them are not Holmes. If Mycroft isn't a Holmes he starts distancing himself from the family and tries to find his bio family (or to know more about them if they were the ones to track him down). He tells Sherlock he has x number of days to arrange for the protection of his parents/other relatives if he wants them to be protected before he cuts them off as well. If Sherlock then Mycroft does him the 'favor' of finding his bio family before no longer helping to bail him out. Of course, this doesn't mean Mycroft's parents (or his technically adoptive parents, if that's where you are heading) are happy and agreeable. The could very well agree or they could make it very clear they view them both as siblings and sons and try to shower them all with attention.
Mycroft ...why is he doing this? I will leave that up to the author if someone decides to fill. It could be he genuinely doesn't want to attach himself to 'not-family' or it could be done because he knows its a lie and a trap. Or maybe he is lashing out because he feels his whole world has tilted and it's a very stressful time. You could throw in other things like omegaverse, magic or what have you to offer more explanations.
Bonus: He eventually comes to his senses and realizes he has made a mistake.
Bonus: Sherlock is grown up. He may act like a five year old and throw epic tantrums but he is a grown up. He doesn't fall apart the minute Mycroft is no longer there but he does begin to realize life is SO much easier with a big brother.
Bonus: This all happens post-BBC Sherlock and is why Sherlock is so pissy at Mycroft all the time. And why Mycroft can be overbearing sometimes (he's making up for it).
Bonus: Sherlock is still labeled a person of interest but now this is harming more than helping.
You aren't my brother-Mycroft and Sherlock (and family)
Turns out one of the Holmes boys is not actually a Holmes. Mycroft drops all protection/guards/'sponsorship' to Sherlock because he (either Mycroft or Sherlock) are no longer related in a brotherly way.
Expansion or prompt:
Basically, somehow Sherlock and Mycroft discover that one of them are not Holmes. If Mycroft isn't a Holmes he starts distancing himself from the family and tries to find his bio family (or to know more about them if they were the ones to track him down). He tells Sherlock he has x number of days to arrange for the protection of his parents/other relatives if he wants them to be protected before he cuts them off as well. If Sherlock then Mycroft does him the 'favor' of finding his bio family before no longer helping to bail him out. Of course, this doesn't mean Mycroft's parents (or his technically adoptive parents, if that's where you are heading) are happy and agreeable. The could very well agree or they could make it very clear they view them both as siblings and sons and try to shower them all with attention.
Mycroft ...why is he doing this? I will leave that up to the author if someone decides to fill. It could be he genuinely doesn't want to attach himself to 'not-family' or it could be done because he knows its a lie and a trap. Or maybe he is lashing out because he feels his whole world has tilted and it's a very stressful time. You could throw in other things like omegaverse, magic or what have you to offer more explanations.
Bonus: He eventually comes to his senses and realizes he has made a mistake.
Bonus: Sherlock is grown up. He may act like a five year old and throw epic tantrums but he is a grown up. He doesn't fall apart the minute Mycroft is no longer there but he does begin to realize life is SO much easier with a big brother.
Bonus: This all happens post-BBC Sherlock and is why Sherlock is so pissy at Mycroft all the time. And why Mycroft can be overbearing sometimes (he's making up for it).
Bonus: Sherlock is still labeled a person of interest but now this is harming more than helping.