for short adjectives we use: adjective+er+than for comparative and the adjective+est for superlative e.g. he is cleverer than his sister. she is the cleverest girl in class. for longer adjectives that have more than one syllable we use more adjective than for comparative and the most+adjective sor superlative e.g. the lion is more dangerous than the fox. the lion is the most dangerous animal.

More friendly

If there are two people mentioned in a single sentence, it is better to say more friendly. If there is only one person mentioned in a single sentence, it is better to say friendlier. Examples: Bob is more friendly than Mary. Bob is friendlier than Mary. Bob is friendlier. The cat is more friendly than the dog. The cat is friendlier than the dog. The cat is friendlier. If Bob is "more friendly," he has to be more friendly than someone else. For friendlier, it can stand on its own or be used to compare two people in the same sentence. So, it depends on the situation that you use each one.

To say friendlier you need then to say THAN and specify what. His is friendlier than I. In the USA More friendly is not used very often. If you want to say someone is friendly or exceptionally friendly we say...... He is very friendly. Or.... he is the friendliest teacher I have ever met. If you want to use more friendly..... then again you have to use THAN.... She is more friendly than her sister. But to us in the USA this is an awkward statement. FOFA has a good point about words like dangerous. You can say dangerously as in...... He came dangerously close to the edge of the cliff. This would mean he was so close that he might have fallen over the cliff. But we have to use most dangerous, or more dangerous for other comparisons. I see from all the answers that you are going to have a challange deciding which is correct. :-)))

Everyone is more friendly than DP. :P