Blackwell retired from boxing after he suffered bleeding on his skull and was put in an induced coma in a loss to Eubank in March.
Eubank Jr will be defending his British middleweight title for the first time.
"I'm not going to let a situation like what happened in my last fight affect my future performances," he said.
The fight against unbeaten Doran, 28,  is on the undercard of Anthony Joshua's IBF heavyweight title defence against Dominic Breazeale at London's O2 Arena.
Blackwell woke from his coma a week after the fight, which was stopped in the 10th round, without requiring an operation.
Eubank Sr, who was a two-time world champion in the 1990s, admitted he lost his killer instinct after the 1991 rematch with Michael Watson that left the latter with near-fatal brain injuries.
But Eubank Jr, 26, said that would not happen to him as he and his father are "two different men".
He added: "Something like that might affect someone's fighting style and mindset. For me, I've used it to fuel myself even more.
"I'm in there to win, defend myself and attack, and to further my career, so there is no mercy.
"It's the referee's job. It's not for me to have to say I should ease up."

Vithiya Alphons, 24, has acute myeloid leukaemia but her Sri Lankan background makes the search hard as not many South Asian people are on donor registers.
She launched a social media campaign  to help find a match.
Charity Anthony Nolan said 5,600 have signed up in the last week.
"The impact of Vithiya's appeal has been nothing short of incredible," said Ann O'Leary, head of register development, at the charity.
"But Vithiya still needs to find her stem cell match and there are people just like her all across the world who are still waiting.
"We need to continue to diversify the register so we can find a match for all."
Miss Alphons was diagnosed with the aggressive form of blood cancer after falling ill just days after returning for her final year as an optometry student at Cardiff University.
She started feeling unwell with severe sickness and a fever, while she had a pain in her leg, so she went to her doctor for tests.
She underwent chemotherapy in Cardiff before being well enough to be transferred to a hospital in London, where she is from.
After her third course of chemotherapy, Miss Alphons felt better and thought she had beaten her illness.
But further tests showed the leukaemia was still in her blood and doctors told her the best option was a stem cell transplant from a donor, which is needed in the next two months.
Speaking to BBC's Asian Network Miss Alphons said she is grateful for all the support.
"I would just like to say thank you so much to everyone who has registered so far and please, please do carry on registering because you can save my life and you can also save so many other's lives.
"Please spread the word and help me to save my life."

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21 October 2014 Last updated at 09:51 BST
Eleven-month-old Harmonie-Rose Allen became ill in September and was rushed into Bristol Children's Hospital where she was diagnosed with a rare form of meningococcal septicaemia.
Harmonie-Rose's family want to raise money to help with her care and have stuck pink ribbons all around the estate where she lives.
BBC reporter Ali Vowles went to meet the family.
Chris Eubank Jr says he will not be affected by his last fight with Nick Blackwell and has vowed to display "no mercy" against Tom Doran on Saturday.
[NEXT_CONCEPT]
Thousands of people have come forward following a worldwide appeal to find a stem cell donor for a Cardiff University student who needs a match in the next two months.
[NEXT_CONCEPT]
A fundraising campaign is under way to help a baby girl from Bath who has to have all of her limbs amputated after contracting meningitis.