That mutual support was necessary during their teenage years when their parents, who have always backed their football dreams, divorced.
While living with their father they were forced to use their initiative on the streets of Freetown to make ends meet.
“Things were hard for us at some points,” Alusine said.
“My brother and I decided to do something just to survive while going to school.
“We were fetching water, putting it into jerrycans and selling it to people in our community. We were also going around collecting used [scrap] iron and sold it.”
According to Alhassan, their bond has been key to their football careers – which were largely spent together until Alhassan moved to a Qatari club last year.
“We love each other so much that we never wanted to be separated,” he explained.
“When a Spanish club, Real Balompedica Linense, wanted to sign me in 2019 I told them that I would only accept their offer on the condition that they also signed my twin brother.
“They told me to sign the contract and assured me that my brother would join me in Spain a few months later – which he did.”
Key moments in their careers have been shared, with the brothers making their first senior appearances, top-flight bows and international debuts in the same games.
Years of playing together has forged an innate understanding on the pitch.
“I can read his mind and he can read mine,” insisted Alusine.
“When I have the ball my brother knows what I’ll do with it and what he should do, so the first person I look out for to give a pass is him.
“We’re protective of each other too. When one is fouled by an opponent the other gets concerned.
“We’ve been fighting for each other since childhood and the pitch is not an exception.”