A courier system was risky. It was too easily breached; someone could intercept and steal the books, or compromise the people involved. Having them out in the open, out of Raven's hands, or his, seemed unnecessary, as long as she had chosen him to help her look after them.
"It would probably be safe for you to come here," he suggested. "You would just need to get word to me whenever you needed to use them." The Cave was a secure location. Even if someone or something did manage to get past his defenses (which he planned to reinforce, now that Raven had pointed out a flaw) this was a better vantage point to fight from than out in the open.
He thought for a moment. Using a common acquaintance as a go between might work, but would be too much trouble. Besides, Batman would rather not drag any more people into this than necessary. The fewer who knew the books were here, the better. "Follow me."
He led her down to an area of the Cave that had been delineated as a workshop. It was mostly immaculate, with the exception of a few projects laid out on tables, waiting for him to return and continue tinkering with them. Rows upon rows of batarangs in various forms hung on a rack, and other gadgets familiar to his arsenal sat freshly made and ready to be stored for future use.
In a cupboard containing an array of communication devices, Batman withdrew one the size of a keychain. It was ovular, and only by looking closely could you tell the shape formed a stylized bat. "Push up like this," he showed her, using his thumb to slide the long side upward vertically. It opened to reveal a small screen with a clock on it. It was currently set at 0:00am.
"When you want to come here, set the time you intend to arrive, then press your thumb against the plate for identification purposes. When the time comes around, wait until the screen turns green. We'll have lowered any security and made any preparations." Handing it to her, he said, "Press your thumb against it now to set it."