I never actually noticed how tightly he was holding onto her. Looking at this I realize now that he wasn’t holding her to shield her from the flames, but to stop her from putting herself in harm’s way.
In the span of about two seconds, Alphonse recognized that he needed to both throw up a protective barrier between them and the fire, and stop Riza from getting herself killed attempting to protect Roy.
At 14 years old he picked up on the intimacy of Roy and Riza’s relationship and integrated Riza’s breakdown just moments prior into his understanding of her as a person, and then used that information to both recognize that she would act impulsively and take action to stop her from doing so. All in the span of approximately two seconds.
This kid is way smarter than anyone seems to give him credit for. He can think on his feet and make snap decisions, and evaluate people’s behavior really quickly. He can do all three at once.
More love for Alphonse Elric please.