He doesn't

I lay in bed for what feels like hours, internally begging for sleep. It won't find me, and I know exactly why: boobs. I know that sounds a lot like Issei's brand of stupidity, but you try sleeping with those melons pressed into your back! God, I'm gonna be so tired tomorrow... "Son?" Ah! Rias is awake. Why? "Why are you still up?" Well, time to lie.

"I guess I'm just not tired..."

"Oh, I can fix that." As she says that, I feel the weight vanish from my side. Is it possible she understood me that well? Whoever made these robots must be a genius! I turn over onto my back, ready to relax into slumber, but as I close my eyes, I feel a slurping at my crotch area.

"Ahh!" As I throw the covers back, I see Rias's crimson hair where my penis should be, and as she looks up, it becomes clear she was behind the sensation. "What are you doing?!"

"I'm helping your body tire itself out. You were rock hard when I looked for what was keeping you awake. Problem solved." Without pause, she continues sucking. It's indescribable, but what I can say is that it's good, the best sensation I've ever experienced. As I release, a calm tiredness does wash over me as I relax into the bed. The last thing I feel is Rias putting the covers back over me and rejoining by my side.