"That isn't surprising," Severus replied, rising momentarily so he could pick up Gaia before she chewed off the ear of her own costume, and he settled her in his lap, and Lysander promptly began fussing over 'his baby'. "Regulus has always been cautious where his emotions are concerned. I have no idea if it is innate, a product of being both a Slytherin and a Black, or a combination of both, but he has always been that way, even when he was an adolescent. I imagine becoming involved with another Snape after what happened the last time and one who was involved with his brother to boot has something to do with it as well."