Niall did a lot of things nobody knew about.
Specifically, things to Liam.
Niall knew this was going to happen.
How?
Liam has fucking told him.
Ever since Liam entered the chat Niall, being a Liam stan, private chatted him often. In fact, Niall even knew what Louis had said to Liam right before "it" happened.
He scrolled through the numerous texts between him and Liam.
payno: Niall look what Lou texted me
new picture message!
It was a screenshot, and it was basically just a worried Louis frequently texting Liam.
Niall now regrets not telling anyone about these texts until now, and even now, he's only telling Zayn.
payno: im fine right? niall im prefectly fine, why does he keep asking me?
At the time, Niall just wanted to make Liam happy. He was sure Liam didn't just have depression,because he always asked Niall things like 'Aren't I happy?' or 'Aren't these pills working, Niall?'
payno: im going to prove to louis that im fine, ill take these pills. that will show him that im perfectly fine.
And that's what happened.
Niall took in a deep breath. He thought that Liam hadn't taken his pills that day, he never dreamed that it could be overdose. He poured out everything he knew into the message he was about to send to Zayn.
He read over it.
He made some changes.
He read over it again.
Made some more changes.
And then Niall finally hit send, praying that Zayn didn't hate him afterwards.