FEMA is an acronym for:
Fédéral Emergency Multiverse Agency.
As in the acronym FEMA's task is to keep peace in the other multiverses from treats that may be too big to overcome by the peace keepers of there own universe,or by multiverse threats,threats that can voyage through multiverses and must be stopped at all cost.
How did FEMA found about multiverse travelling?
Well it was back in early 2004,nothing really happen that year for civilians but for l'ANGE(Agence National de Gestion de l'étrange) that eventually became: FEMA,it was a whole different thing. l'ANGE has bases all around the world and get funds from almost all nations worldwide,they keep peace since 1978 that was the founding year of L'ANGE .L'ANGE's vocation back then was to research on weird things that normally wouldn't be explain by normal science,Thats how they came up with a sub-agency called: L'ANGE containment ,it is suppose to keep the one of a kind object with special properties that shouldn't work with our world's physics.
So what happened in 2004?
Some agents that went rogue decided that they would be able to manage l'ANGE way better then the ones at governance now so on the 19 of september 2004 they tried to attack the international base under the UN headquarters in New-York,the attackers managed to kill the head of L'ANGE and wounded/killed several regional leaders, before the attackers got sucked into a rift...a dimensional rift,Luckily for the survivors the rift closed itself 2 minutes laters. After further inspection they found a weird bracelet looking device that would soon open the door to the multiverses for them.
The day after the incident,L'ANGE debated on a new leader,between the regional leaders and after a week they finally voted for Michael Morin,the director of the Québec base where he leaded successful missions to keep peace,he was going to miss his agents but he now had the whole world to take care of and one of his first resolutions was to make the bases heard about that bracelet shaped device and told his teams of scientists to work on it,what they discovered changed L'ANGE forever that's when they changed their name to: FEMA to make it fit with there new vocation to: protect all multiverses from harm.