I wrote the sentence:
Walking into the room, Zion was standing at a tall drafting table putting together what looked like a space station with his legos.
When using brand names for toys, should I write Lego or legos or Legos? Because there's more than one lego. I was thinking legos, but I know the brand name is Lego.
In description, unless you're trying to capture a folksy voice, they're Lego bricks, with a capital L (it's a trademark). An individual one is a Lego brick, or just brick.
Of course, people sometimes call them Legos in real life, so you could use that term in dialogue, even though it's not officially correct. I would still give it the capital L though.
By convention, trademarks are capitalized. So a drug name like Zantac is capitalized, because it's a trademark, but heroin would not be. However, heroin used to be a trademark (it was a Bayer product), and would have been written Heroin. Now it has become a generic term for the drug and is lowercased. Similarly, tarmac (the stuff they make runways out of) is written lowercase these days, but was a trademark.
It's not usually the writer's responsibility to protect a manufacturer's intellectual property rights. Capitalizing a trademark is all you need to do, and you should not add trademark® symbols™, unless you're working for the company that owns the trademark and they insist on it.
If you don't capitalize a word like Kleenex or Lego, you or your publisher are quite likely to get a letter from the company's lawyers advising you to do so in future. A company that doesn't take these steps to protect its trademark is likely to lose it.
I don’t think trademark has anything to do with it. “Lego” is a proper name, so you capitalize it. If there is more than one, you put an “s” on the end to show that. So you get “his Legos.” You would also write “Bill” or “Stan” or “Rover” or “Google” or “MacBook” with capitals, and only some of those are trademarked. If someone carries 2 MacBooks, you could write “his MacBooks.”
