Reflet

Call her Female Robin and she may kill you.

Unfortunately not getting her own amiibo despite her popularity, this has caused her some anger issues... Well, that's not the only reason. She is easily flattered and embarrassed and is a little bossy. She'd rather be alone or at least think she is alone then say... Hang out at a party where everyone is getting drunk, of course her mind will change about this if her brother is going.

Plot
Found in the library along with her brother, the two were immune to literally everything since they were so absorbed in their reading.

Falco tells everyone to break the 4th wall, which causes sirens to wail throughout the mansion. Reflet and Robin quickly react, jumping from their position to fix it with an emergency button push.

After a bit of scolding, Reflet (and Robin) decides to join the group, in promise of some help finding an S-Support mate and that they get to actually do what their class states once more.

History
Born a few minutes after Robin, she is the younger of the two. She was born only to be the vessel for Grima, as was her brother.

While Robin was trained to be the vessel, Reflet was trained in the Art of swordplay by her mother, and other things. But the training had to stop when her mother ran away with Robin at the age of 7, missing out on an opportunity to take Reflet.

Now Reflet stuck with her father, she had to be the new Vessel. It took longer to train her body because she was more stubborn and she helped in fighting off enemy armies so that cut into preparation time.

She eventually ran into Robin once more and managed to absorb Grima. Robin then killed them both in order to save the world from anymore Grima.

Later, both were revived and found alive by Chrom, with Reflet having forgot what just happened. She then lived with her brother until getting invited to Smash.