OMG they are definitely Grace and Clay!!! Even their colors match.
I guess that Lucien is a Betta fish. They can be friendly to their keepers but aggressive with other betta fishes, engages in fights with other Bethas that end up in death.
Farah would be an angelfish, smart, playful, can confuse smaller fishes with food, will fight for her space.
Olivier would be a smol ordinary goldfish likely to be bullied by the other two.
They would be in the same tank and the pet owner would be praying daily that they don't kill each other.