There probably isn't any physical risk to Alex if he gets "active". I've had cockatiel chicks mating with each other as young as five months, and I've heard of them doing it as young as three months. I don't know whether he'd actually be able to fertilize an egg at this age, but if he did it's not likely that he'd be a good parent. Lucy would probably have to raise the babies by herself. She's also pretty young but more likely to be a good parent than he is. Young cockatiels are like human teenagers - they're physically able to make babies before they're mature enough to deal with the responsibilities.

If she lays an infertile egg, you can just leave it where it is as long as it doesn't get cracked or broken (which would be a bacteria hazard). It's not going to hatch anyway so you don't have to worry about whether it's safe or stays warm enough. If she lays an egg that might be fertile and you want to let it hatch, you could put something that won't tip over in her nest area (like a heavy bowl or basket or a cardboard box that's been cut down so the sides are a couple of inches high), with wood shavings in it for padding, and put the egg(s) in the middle of it.

A drawer would seem like a good nesting place. I once heard of someone whose cockatiels liked to play in her underwear drawer so she left it open for them. She didn't think anything of it until one day she heard babies cheeping in there. Makes you wonder how often she changed her underwear if a pair of birds could lay eggs in there and incubate them to hatch without her noticing.

They couldn't nest on top of the drawer lol thats where the stand and their food is and they are throwing the newspaper on the floor.

makes me think how come that her birds spend all nights in that drawer, because eggs need heat at night too I thought

maybe that's her spare underwear drawer

She must have a LOT of underwear if she needs two drawers to hold it.

Haha lol

They could have also managed to hide the eggs under some pairs too, if in the case they're not in there at night.

I've also noticed that Lucy has acted a little more needy lately, as well. The other day when I had her out, she was wanting attention almost as much as Alex (and Alex wants attention 24/7). Today she's had the tendency to scream non-stop for me whenever I leave the room. Thought I finally got her to break that habit a long time ago. I wonder if the hormones have anything to do with this.

She also has a head full of pin feathers due to molting, so she's not in the best mood.

Despite Lucy's stubbornness and independence, we seem to have formed a strong bond. She lets me pet her even when there is barely any light and she has trouble seeing me. That is something even Alex doesn't let me do. I wonder if that trust has anything to do with me getting her back after she flew away that one time?
Or maybe I've had her long enough to form such a bond. It's hard to tell. I'm glad to have a bird like her. I love having Alex too. They're both so full of personality!

I have to add, how little someone must be watching what her birds are doing, if she didn't notice they were sitting on eggs for almost 3 weeks

Cockatiels don't have good night vision in any case, but Lucy's is probably better than Alex's. Red-eyed birds are said to have poorer vision than dark-eyed ones, and my dark-eyed birds certainly seem to function better in dim light than the red-eyed ones do.

That must be true, bhc have bright red eyes as an adult. N zorro dosent seem to care for the dark. His eyes arnt red yet, but they gone from dark brown to light brown. Im told by 1yr to yr n half b bright red.