Trident/net fighter?

[UnwiseAlistair]

So I'm taking part in a new campaign and I'd like to play a net/trident style fighter like a roman gladiator. I want to make this build as good as possible while sticking to the interesting but slightly un-optimized fighting style. We're starting out at level 2, so I'm hoping for some ideas on how to make this work as well as possible while sticking to the idea.

[Cl0001]

To get the net to work you'll either want sharpshooter or crossbow expert. Because otherwise you'll technically always have disadvantage on using the net. I would definitely go battlemaster when using a net. That'd be my big recommendations. Everything else is kinda up to you in terms of effectiveness

[ThurlRavenscrof]

Agree with crossbow expert. I'd probably go battle master so you can do gladiatoresk tricks. Probably a dex based fighter with some sort of medium armor?
It's hard to make it a killing machine when gladiators were designed to entertain crowds not survive battles

Go entertainer background though!

[Specter]

I don't think it's unoptimized at all.
- Grab Crossbow Expert (aka Net Expert)
- Get the feinting attack/precision strike maneuver for advantage/bonuses with the net
- Maybe two rogue levels for cunning action?

[JellyPooga]

If you want a true Retiarius character, they traditionally had very light or no armour and specialised in fighting against very heavily armoured foes (albeit, they were expected to lose, or at least the odds were typically against them in such matches). To that end, a level in Monk or Barbarian might be an idea for Unarmoured Defence. There's no ability I can think of that "specialises" against heavier armour, per se but someone else might be able to think of something.

[Aerogellin]

If your GM allows Unearthed Arcana you also might look at the Close Quarters Shooter combat style (Fighter, Paladin, and Ranger only) in the Underdark UA, which will eliminate the disadvantage for ranged attacks when you're within 5 ft, this of course includes the net. If you're not playing variant human for a feat it also could help you get your desired playstyle online at the start of the game.

Be forewarned that nets cost a bit in the early levels, depending on how much gold your GM is throwing around. They're easier to destroy than to ability check out of, and each time they do you're out 1 gp and a trip to a vendor. I'd suggest some kind of backup playstyle in case you run out of nets!