Gestating characters feels something like the mental equivalent of gestating a baby. In both cases, to create them you lose yourself. Or at least you reshape yourself to encompass them.
Ann BrasharesCarmen sat up when she heard a familiar trill from her computer. It was an instant message from Bee. Beezy3: Packing. Do you have my purple sock with the heart on the ankle? Carmabelle: No. Like I'd wear your socks. Carmen looked from her computer screen down to her feet. To her dismay, her socks were two faintly different shades of purple. She rotated her foot to get a view of her anklebone. Carmabelle: Ahem. Might possibly have sock.
Ann Brashares