Your example is not similar because the adjectives little and strange describe two different aspects. The words blue and yellow both describe the same aspect: [color=blue]color.
If you have two adjectives describing the same type of aspect of one noun, then you should connect the two adjectives with and: a blue and yellow flag.
If you have three adjectives describing the same aspect, then you should use a comma between the first two and the word and between the second and third: a yellow, blue and white flag.
By the way, in your sentence, I would prefer this word order:
1-He is a [color=indigo]strange little fellow.
A good rule of thumb for adjective order: (Remember? :))
Opinion or judgment [color=indigo]i[/i]
Purpose or Qualifier
Keep in mind, this is just a general rule of thumb. Sometimes it doesn’t work. There might be a standard collocation that is a little different, for example.