What's a normal reaction to trauma vs. when should I be worried?

I am so incredibly sorry for your loss! I’m definitely not an expert here, but I can share a little bit of what my family went through
When my grandma passed away, things were already pretty messy with a bunch of family arguments going on, and my mom was the one who found her. For those first few months, she was just completely out of it—totally lost and spent most of her time just crying. Things eventually leveled out a bit, but she still dealt with these really heavy bouts of depression for about three years after that. During that initial stretch, she was on prescription meds like Lexapro or something similar just to keep her head above water, and honestly, that was pretty much all the help we had at the time. I think I was really the one who kept our family from falling apart, because I just made this internal decision that we had to keep things functioning as normally as possible. I ended up taking care of everything around the house and kind of subtly nudging everyone else to snap out of it and practice some self-care, almost like I had to step up and be the parent to them for a while. From what I can tell, your brother seems pretty level-headed, even if he’s probably dealing with a massive storm of emotions inside; he'll get through this. He just needs space to let the grief out on his own terms. It took me about three or four years to actually give myself permission to grieve properly, because before that, I was just totally blocking everything out. I seemed okay on the surface during that time, even though I was hurting deep down, and even now that it's getting easier, I can finally talk openly about how much it actually wrecked me. Everyone grieves differently... just be there for him and show him you've got his back!

First off, I am so sorry for your loss.

It’s good that you’re looking out for your brother and staying ready to call in the professionals if things head south.
Typically, the grieving process can stretch from about a month to three months, though everyone's timeline is a bit different. During this window, most experts wouldn't even recommend jumping straight into therapy; it's too early to tell if this is just standard grief or if it's evolving into something more clinical. Grief is highly personal, and no matter how messy it looks on the surface, it’s a normal part of processing loss. It doesn't automatically mean he's sliding into depression.

If the symptoms linger significantly longer than that or start getting worse, then yeah, seeking professional help is the right move.
You should also keep an eye out for signs of dissociation—things like him being unable to recall specific details or the event as a whole, or having an emotional reaction that feels totally disconnected, like he's numb or claiming nothing actually happened. Other red flags include recurring nightmares or intrusive, unwanted memories of the incident.

It’s hard to say anything truly profound about something this heavy, but I guess I can offer my two cents if it helps at all.

Losing a father to suicide is just... it's devastating. There's no other way to put it. But I suppose the human psyche is kind of like a tree—it has roots and branches reaching out in all these different directions. I don't know what the relationship was like between your brother and his dad, so I realize grief moves at its own pace and looks different for everyone. That said, I think what keeps a person grounded is the web of connections they have with the world around them—everything from work or college, to a girlfriend, buddies, hobbies, even just going for walks, the food they eat, their clothes, where they live, stuff like that. If all those connections start snapping one by one, and if someone stays withdrawn for too long without any genuine, loving support to lean on, I honestly don't think that's a good sign.

Since you guys aren't living in the same city, maybe there isn't a whole lot you can physically do to help him right now. But, I've always been a bit of a believer in those weird, almost psychic connections we have with people. Something tells me that we can actually influence each other just through the way we direct our thoughts. Maybe try sending some prayers or just some really positive energy his way every once in a while.

I feel like you might be able to help him indirectly just by being present and doing things with good intentions. You probably don't want to push the conversation about his dad too hard, and you shouldn't overdo the condolences either, but you also can't act like nothing happened. It's a delicate balance. Just find a way, a time, and a middle ground where you can both express that you care and that you're there for him through this.

Thanks for all the input

I’m pretty sure our family is tough enough to handle whatever comes our way—nothing is going to break us

But just in case, I wanted to have all the facts on hand if things go sideways... honestly, it’s just so I can get some sleep at night

If those "textbook" symptoms end up lingering longer than anyone would expect, I figure that’s really when it’s time to start getting concerned...
In any case, people like that just need a little extra time to process everything.

Look, I’m no expert, but from what I’ve read, grieving doesn't have to be limited to just a few months. I'd probably suggest seeing a therapist after those first couple of months anyway, just to tackle the same questions you're asking here.

No matter how massive the trauma is, everyone reacts differently based on their own personality. Trauma itself doesn't break us; if someone does break, the trauma is really just the trigger. (And I'm talking about adults here, like you and your brother).

Sure, everything is subjective on an individual level. But fields like psychology and psychiatry strive to be exact sciences, which is why they rely on standardized benchmarks. Just like we have an average IQ, there’s such a thing as an average grieving period. These metrics exist for a reason; if someone seeks professional help, the first question a clinician asks is usually, "How long has it been?" If it hasn't been long enough, they won't start treatment yet. It’s that fundamental.
And I used the range of 40 days to 3 months because the clinical "benchmarks" vary slightly between American and European standards.
I think my point came across clearly enough.