Both of them were good friends during the time Zayn was in the band.
Niall used to consider Zayn as his best friend. He used to tell him everything, even when he was in love.
Whenever they were mobbed, Zayn always searched for Niall first.
Niall once tweeted, "I got the lads Christmas presents except for @zaynmalik. I don't know what to get him". Zayn replied, "@NiallOfficial, you don't need to get me anything. Being with you is enough."
Zayn once said that if he could swap his voice with any of the other boys, it would be Niall.
Zayn once ate Niall's last chip and as a punishment he tried to eat Zayn's hand.
Talking about Zayn, Niall said, "Everytime I hang out with Zayn, I feel like I'm cool too."
They used to hug each other once at every concert.
Niall used to annoy Zayn by singing everything in opera. One morning Niall started singing in opera and Zayn slapped him.