Re: Reactions - Missy Steve is pretty inconsolable. He's there in the control room, smashing buttons and shouting into the communications device. "Tony! Tony, are you there? Come in. Come in, Tony!" And then the instant he decides to go in after him, the portal closes. He turns around and uses his Captain America voice to the sciencey people "Get it back! Turn it back on! Get the portal back!" ...but to no avail. He stays for a long time in the portal room with whoever is there pushing buttons, pulling levers, turning dials, and won't leave until it seems like all hope is lost.
Peter finds out from May. This is another blow. The poor kid has lost too many people for someone so young. He's beside himself with worry, but also determined to do something. He and May go to find Cisco--the first person Peter thought of who knows about portals.
Kate will probably hear about it from Clint, and will be really bummed out. She doesn't really understand all the sciencey stuff, and will be concerned that this means she's still in danger of being randomly swallowed by a portal. And then she'll feel massively guilty for thinking about herself when so many people are hurting.
Sharon will reach out to Pepper as soon as she hears. I imagine it'll take a while for the news to spread--dunno who will tell her. She has contacts and skills that can help take some of the pressure off of Pepper--Sharon can take on some administrative stuff so Pepper can do whatever she needs to do right now. Sharon and Tony were on good terms, so she'll be bummed out... but she'll keep a stiff upper lip and help.
Henry is kinda part of the science team. He's helped with some of the portal stuff, and will be there when it all goes down. He's got his own instruments to observe and log data. He'll have records of the entire event for them to look over later, try to figure out what happened. He'll be in shock and have no idea what to do next. He wishes that Magnus was here. Or Tesla. Tesla would be even better.
Cath really liked Tony. She's going to be very sad, and deal with it the only way she knows how--by cooking and sending a lot of food to the Facility. Things will be fully catered for a couple of days. Of course, she doesn't have a heart so she won't be devastated the way someone with a heart would. But sad nonetheless.
Yelena doesn't care much. XD Sorry, Tony. She's more concerned with how this will affect her sister.