"Payno, my beloved friend, one of my best friends, my brother, I love you, buddy. Sleep tight", writes Tomlinson.
Tomlinson was 18 years old and Liam Payne 16 years old the first time they met. Payne died on Wednesday after falling from a great height from a hotel.
"Liam was, in my opinion, the most important part of One Direction. His experience from a young age, his perfect pitch, his stage presence, his writing was a gift" writes Tomlinson.
He also turns directly to his lost band colleague and explains that he wants to be like an older relative for Liam Payne's seven-year-old son, Bear, in the future.
"I want you to know that if Bear ever needs me, I'll be the uncle he needs in his life and tell stories about how amazing his dad was. I wish I had the chance to say goodbye and tell you one more time how much I loved you."
The other members of One Direction have also written personal posts about Payne after his death.
