Unless anyone else wants to jump in first, I'll go to try and finish disabling that interceptor. Since the Gain the Advantage action failed, do I have to add setbacks for defense from the fighter?
Actually, the Interceptor's Maneuver on its last turn was to move to Short range, not Evasive Maneuvers, so Gain the Advantage wouldn't have made any difference until it did use Evasive Maneuvers on its next turn, well except that now the Interceptor can choose which of his defense zones gets attacked. So your attack would be Average because the Interceptor is only 1 silhouette lower than the Serendipity.