Mr Lasini said his son lived his short life "full force''.
"He was resilient, cool, strong-headed, had a maturity beyond his years and knew how to accept a challenge and overcome it,'' he said.
Darius' parents are separated. Mr Lasini said the last time he saw his son was last month.
"I was with Jordan, his big brother, it was an unexpected catch-up. I asked Darius, was he happy, and he said he was. And that meant everything to me.''
One of Darius brothers managed to tell the service: "He was the best brother.''
But his mother Pania Claxton could not bring herself to speak and had a statement read on her behalf by relatives.
"Darius my darling wee pipi, always keeping us on our toes. We never knew what mischief would come with each tomorrow, and there was a lot ... Darius, I wasn't prepared for this, and don't know how to say goodbye.
"There are so many things I didn't get to see you achieve ... your brothers are heartbroken without their wee bro D ... you know we will always love you D. Miss that cheeky smile.''
A spokesman for local child and youth support organsiation Agape Trust told the service at Canterbury Crematorium that he hoped Darius' death would act as a "wake-up call'' to youths experimenting with drugs.
Detective Sergeant Earle Borrell said later police had identified the store where the youths are believed to have bought the butane and spoken to the owners.
Inquiries are ongoing and it was unknown whether charges will be laid.
Darius' death has been referred to the coroner.
A Facebook page, The Little D Support & Donation Group, has been set up to highlight the dangers of butane-sniffing and to seek donations to support the family.
The group is planning a candlelit vigil at New Brighton Pier in honour of Darius. A date is yet to be set.
