"It's okay," Merlin say, voice terribly thin. He doesn't expect Regulus to be thinking especially rationally, right now. "The base is flared, you can't - lose it."

He knows he's walking a narrow line here, but he can't stop himself from reaching out to take Regulus' wrist in his hand and slowly push the remaining length inside him, making his body swallow up the (currently, almost unnoticeable) swelling of the knot.