The ending that you're referring to doesn't require you to have 100% Paragon or Renegade, but rather

but rather that you have used a Paragon or Renegade conversation option on him at every other opportunity

From the Mass Effect wiki:

There are several conversation branches with associated Reputation checks, but the conversation's outcome hinges solely on the final choice. In order to use the final Paragon/Renegade conversational options with the Illusive man, you must have used a Paragon/Renegade options on him at every other opportunity in the campaign, including the meetings on Mars, Thessia and the Cerberus base (which were discovered through other dialogue options.

The ending that you're referring to doesn't require you to have 100% Paragon or Renegade, but rather

that you have used a Paragon or Renegade conversation option on him at every other opportunity.

From the Mass Effect wiki:

There are several conversation branches with associated Reputation checks, but the conversation's outcome hinges solely on the final choice. In order to use the final Paragon/Renegade conversational options with the Illusive man, you must have used a Paragon/Renegade options on him at every other opportunity in the campaign, including the meetings on Mars, Thessia and the Cerberus base (which were discovered through other dialogue options.

The ending that you're referring to doesn't require you to have 100% Paragon or Renegade, but rather

but rather that you have used a Paragon or Renegade conversation option on him at every other opportunity

From the Mass Effect wiki:

There are several conversation branches with associated Reputation checks, but the conversation's outcome hinges solely on the final choice. In order to use the final Paragon/Renegade conversational options with the Illusive man, you must have used a Paragon/Renegade options on him at every other opportunity in the campaign, including the meetings on Mars, Thessia and the Cerberus base (which were discovered through other dialogue options.

The ending that you're referring to doesn't require you to have 100% Paragon or Renegade, but rather

but rather that you have used a Paragon or Renegade conversation option on him at every other opportunity

From the Mass Effect wiki:

There are several conversation branches with associated Reputation checks, but the conversation's outcome hinges solely on the final choice. In order to use the final Paragon/Renegade conversational options with the Illusive man, you must have used a Paragon/Renegade options on him at every other opportunity in the campaign, including the meetings on Mars, Thessia and the Cerberus base (which were discovered through other dialogue options.