I suppose if we AUed it to perhaps him not getting shot? Like someone preventing Lucy before she manages to kill him? Then we could have them perhaps dealing with the aftermath of what happened on the Valiant and maybe going to adventures? If the Doctor can trust him that much. Plus the added torment and amusement of being locked in one place together for a long period of time. I think it probably has the most wriggle room? Like we could go a lot of places with that!