people tend to rip on ignis for being "so ooc" in episode ignis and how he reacts during ... that ... scene- but they fail to remember that he's twenty-two. TWENTY-TWO. not even that much older than noctis and still very, tragically young.
since the beginning, ignis has always put it upon himself to carry everyone- to carry noctis- because that is his duty, and it's something he takes pride in as a person. he's chamberlain and he's a childhood friend. he always has to be the smartest person in the room and he's always expected to keep a level head for the good of the crown, and by extension: its people. ignis has worn so many hats ever since he was taken to live at the citadel to be under the crown's service, being his advisor meant having a cool head and ability to analyze all possible outcomes to ensure noctis' success in all matters.
ignis scientia was essentially groomed from birth, hailing from a family who holds a longstanding service to the crown; so while his childhood left him without want, it also left him with.. a belief system that can do more damage than good. to have it drilled into a child that the crown's wellbeing will always come before their own, that their suffering doesn't matter so long as they are safe.
when ignis is old enough to attend school, he's granted a private education. separate classes apart from everyone else, likely at the citadel or attending a tutor's classroom within the city. the years of physical training he goes through, in order to join the crownsguard. all for noctis' sake. when ignis begins to live on his own, he's in a small little apartment. his car is nothing spectacular, ignis seems to live mostly within his means. he's on call, day and night, just in case his services are needed. it's no surprise that he's a stimulant abuser, on top of it all.
and even when he's NOT at noctis' side, ignis is still in service to the prince: taking notes during council meetings, sewing a buttons back on clothes. researching different recipes and improving his first aid abilities. and it's not to say that he grew up to serve the crown miserably. truly, he found so much to love through the length of his duty and he wouldn't give it up for anything.
but it's THIS that makes his "hasty" decisions to don the ring make so much sense for him. through the recklessness of his decisions, that YOUTH is still there. ignis reacting not based on logic, but emotion, because of what is at stake ( THIS WORLD MEANS NOTHING TO ME. DO WITH IT AS YOU WISH; I WON'T LET YOU TAKE [NOCTIS] AWAY ). putting on the ring was the one decision he made without even truly thinking about it, because his life will always be second to noct's.
for so long, ignis existed as an extension of noctis. THE HAND OF THE KING. from a young age, noctis was made to be his entire world- his purpose. without noct, ignis has NONE. and so when this is threatened, when ardyn all but throws it back in his face ( "hey, how do you feel watching your master in such a state? [...] you must feel really disappointed, right? hoping he’ll become a splendid king, you give everything including your life." ) ignis ... rightfully loses his composure. i won't address the line of ardyn referring to noctis as ignis' master. too much to unpack there i fear.
you see ignis unravel not only mentally, but physically as well. his usually perfectly coifed hair is down and it's messy. clothes are half untucked and his sleeves undone and rolled. he looks so much younger in these scenes and it's a gutpunch of a reminder that he is TWENTY. TWO.
he shoulda been at da club