I was wondering if someone can recommend an indoor bonsai tree that could
be placed in a bathroom - I shower everyday, so there's steam every morning,
and there is a small meshed window, that faces south.
So there's not much sunlight, and I might have to put in some artificial
lighting. Ideally, it should have some red leaves/fruit -

So the poor guy asks a perfectly serious question, and everyone makes fun of
him.
There are tropical bonsai you can use. However, I suggest you get several trees
and rotate them between the bathroom and a growing area, so they will be kept
healthy. A flowering and fruiting bonsai will need more light, as you have
surmised. They will need to be kept outdoors all summer, but you can rotate
them in your bathroom, say a week at a time.
First thing you need to do is get one or more books. Start with something like
the Sunset Bonsai book. If there is a bonsai club anywhere near you, join it.
Suggested species:
Pomegranate (persimmon-red flowers & fruit).
Serissa (white flowers)
Ficus (probably no fruit, but the easiest)

However, if you just want a finished bonsai and you are not interested in
growing or caring for it, you can rent them.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)