Bruce knew he didn't know everything about Selina, just as she didn't know everything about him, but he did know many things she didn't know he was aware of, and what he did know didn't scare him. There were many things in Bruce's past that would perhaps explain to Selina why that was so. He understood what people needed to do in order to survive, and the effect that had on a person. That she was able to now tear through those layers and find something to give to him was a miracle few could expect.
But Bruce was similar to her in that respect - he had built up a shell over the years that he'd had to find a way though, and it was difficult for him to open up. Especially about some things. When it came to his problems - especially so early in their relationship when there were so many of them - he was reluctant to burden her, and them, with so many troubles, so quickly.
"She's as stubborn as a mule and has a chip on her shoulder the size of Gotham, but there's something in her I like. There are other things I don't like - she's too stubborn for her own good, and she'll be the one to use excessive force in Gotham and justify the means with an assumed end. But if I can persuade her... I think maybe we can work together."
Bruce's bathroom had been personally designed for his own needs. The shower, indeed controlled by programs, was stone. It had no doors, but curled inward like a seashell, into seven different adjustable shower heads. and a bench seat. The tub was six foot by four foot and almost level with the floor, and served as a hot tub with different setting, customized specifically for Bruce's needs after patrolling, depending on his level of injury and pain. The stone floor was heated, and towel warmer kept the towels warm as well. It was the only thing worth dragging himself upstairs after patrol on his worst nights.
Not as sure about Luthor's capabilities, Bruce looked grim as the entered said bathroom. "If anyone could destroy Superman, it's Luthor. And he'll have the power to do it. Kal is strong, but he's only one man." He looked at Selina, realizing he'd never referred to Clark by that name in her presence before. "His name is Kal," he said quietly. "Kal-El of the planet Krypton." It wasn't exactly a secret - Lois Lane had revealed his planet of origin, and Clark had been introducing himself as Kal fairly regularly these days. It just wasn't well known.
"I've broken into Luthor's business and residence on more than one occasion," he smiled at her. "Might be nice to have assistance sometime. Whatever else happens - Luthor's not going to hurt him. Not while I have anything to say about it."
Pressing one of the buttons on the controller without looking, the shower came on, steam rising within seconds as the water, automatically hot, hit the stone floor. Wrapping his arms around her, Bruce said, "You should see Stark's shower; it's voice controlled." He kissed her. "Well - everything in his house is voice controlled. It's run by A.I." Tugging, he started backing toward the shower.