>>53240271. You'd have either won or lost, but more Wyverns would show up. You're wearing the uniform of the enemy in the middle of a massive battle. Furthermore you brought a ton of attention to yourself by single-handedly slaying a Demonic Beast. The option to fight existed to punish EXP hungry anons who thought of staying and fighting. This is actually a very common thing that occurs in Fire Emblem maps lol.
2. Blair and Corrine would have struck out on their own. Travelling across Fodlan with just each other and a very, very small group of others. Likely the Circus Trio and maybe a few more people.
>>53240401. Fighting your way through a civilian riot to escape through a small gap within the walls. You'd have met up with Elizabeth here, who would have helped shepherd you through, and join your crew.
2. It would have 100% worked! It was given to you by the Archbishop. Serena would not have questioned your supposed dedication.
3. You'd have fought alongside Leopold and some of the other Knights of Seiros, including Alois and Shamir. It would have been a Survive map, where after surviving a certain amount of turns, the battle would be over and your group would be forced to surrender once surrounded by Rex. You'd have found a way to escape though, with someone holding him off while you got away on Beathan.