With her hand

Lydia lets the cage drop to the floor and wraps her cool hand around your still soft cock" Come on...Get hard for your misstress."
Blood rushes in your dick. The danger of being caught, in combination with Lydias powerplay turned you on more than you want to admit.

"Good boy"

After your penis reaches it full size Lydia smiles satisfied. "There we go. God i missed the feeling of a big dick in my hands."And without taking off her own clothes, she begins jerking you off, fast, and with a hard grip. She clearly didnt plan for you to last long, which you wouldnt if she continued this way. You didnt cum in over three weeks, and Lydia clearly knows what she´s doing.
Faster than ever before, you feel yourself apporaching climax, which Lydia notices.
Right before you´re about to cum, she removes her hand, edging you.
"Tss Tss Tss not so fast." She gives you a moment to recover, then begins again. In this way she edges you for what feels like eternity.

Finally you give in to your horniness and moan: "Please let me cum, Mistress."

“On your knees,” Lydia orders, and you obey, **** to finally cum. Lydia looks down on you for a second, how you kneel in front of her, naked, on the edge, for everyone to see who might enter the apartement. She laughs. "All the storys I heard about you Ethan. The big man with the bigger dick. Marla wouldnt shut up about how you split her in half. And now look at you." She put her feet on the tip of your cock, which was already covered in precum, for a second, "On your knees in front of me, begging to cum"
She seems to enjoy taking this picture in for a couple of seconds, then she crouches down in front of you.

"Your such a good boy, arent you? Fine. I´ll let you cum,"

She gives your dick a couple more strokes, than she removes her hand, and rubs the back of the glans of your penis, the frenulum, with one thinger, until you cant take it anymore.

In a long, almost painful ruined orgasm, you pump load for load of cum moaning, first on your stomach, then on your legs, until its down to a couple of drops drippling down the side of your quivering dick.

Lydia collects some cum from your stomach with a finger and brings it to her mouth. She licks her finger, her eyes closed, clearly enjooying the taste. then she says: "I'm going to take a shower, wait here" and disappeares into the bathroom, not without first putting the cold metal back over your now flaccid penis and locking the cage.

So now you´re there, naked, covered in your own cum, kneeling in the hallway with a chastity cage on.