Show your Gratitude: When your mentor has helped you in completing your work successfully, show your gratitude towards them by helping them in some way. Build your relationship equally by serving them as a source of information and try to support your mentor if you find any opportunity to help them. And while showing your gratitude make sure it wont harm the work of the mentor even more when he is into some professional problem, your information must be valuable and useful. This can help you to build your relationship stronger.