South Wales Police say they do not believe the apparent suicide of 13-year-old Laura Rhodes was linked with bullying.
Laura's family called her 'a beautiful, pure-spirited girl'
Laura, from Neath, died on Saturday after what appeared to be a suicide pact with her best friend, Rebecca Ling from Birmingham.
Rebecca, 14, is recovering in hospital after a suspected overdose.
The girls had met online and there had been suggestions locally Laura had been bullied over her weight.
Laura's family have paid tribute to a "beautiful pure-spirited girl" who, they said would be missed more than any words could convey.
The girls met in an internet chat room a year ago and sparked a police hunt by running away together after a holiday in Greece.
They were found on Friday and taken back to Laura's house in Heol Derwen, Cimla, but were found seriously ill there early on Saturday.
Both girls were taken to Swansea's Morriston hospital, but Laura could not be saved. Police said her death was not being treated as suspicious.
Laura's father Michael, mother Yvonne and brother Andrew issued a statement which said: "Our daughter Laura, a beautiful pure-spirited girl who died on Saturday morning will be missed more than any words can convey.
"She was the most loving and generous person who did not have a nasty bone in her body".
Police are investigating the tragedy and a post-mortem examination is due to be carried out on Laura.
Laura (left) and Rebecca met via an internet chatroom
Rebecca's family hope she will be allowed home from hospital on Monday.
Her mother, Alison Ling, and father David have been at her bedside.
Mrs Ling's partner, Neil Fisher, told BBC Radio Wales: "She's looking good at the moment. She's not getting any worse. She's speaking to her mum and, hopefully, she'll be home on Monday."
Mr Fisher said the girls had left a note in Laura's bedroom.
He said: "The note said they were going to kill themselves.
"We do not know why they took the tablets - that's why the police are talking to Alison.
"Becca says she went into Laura's mum and told her what had happened, and Laura was passed out on the floor - and then Becca passed out. That's all we know."
Welsh Secretary and House of Commons Leader Peter Hain, who is the MP for Neath, said: "This is a terrible tragedy for Laura's family and my sympathy goes out to them at this sad time.
"There are obviously very deeply felt reasons behind this tragedy and I hope that everyone can learn lessons to make sure that this never happens again to vulnerable young people."
Detectives believe the girls' home computers may hold clues about their friendship.
Experts have been brought in to give police access to their e-mails and messages.
Although living 130 miles apart, the two formed a friendship last year and began using MSN Messenger and mobile phone texts to keep in daily contact.
Rebecca had been due to travel home to Longbridge, Birmingham, last Wednesday.
Police said members of Laura's family had dropped the pair off at Neath railway station so they could say goodbye.
But the alarm was later raised when neither girl returned home and although they were found two days later, the episode was to end in tragedy on Saturday.