I believe President Trump had dinner with Comey to size him up as a one who could be influenced by political methods. The dinner was an effort to flatter Comey and see if that flattery could change his direction of the Flynn investigation and the Russian investigation. President Trump wanted to confirm that the strange Loretta Lynch recusal and the end of the email investigation was the result of submitting to influence. That would build the case of obstruction against the Obama Regime. Notice that Comey told President Trump that he was not under investigation. That told Trump that Comey was willing to tell such a lie to garner political favor. Of course President Trump was under investigation. What else was Comey willing to say or do to garner political favor? It would be interesting to know what other tidbits of information Trump was able to pull from Comey at that diner.