Of two friends

I have two friends who are very different.

One is extremely inquisitive to a fault and will stop at nothing to satisfy his curiosity, even when the other party is showing his unwillingness to share further, and even if the incremental information he gets is not material in the betterment of his life.

The other one is guarded to a fault, does not offer any information volunteerily especially on his personal life unless asked and pursued.

I also have two other friends who are very different in another manner.

One is extremely generous and will offer to buy drinks or food, or volunteer his services readily.

The other is a silent acceptor of generosity of goodwill (like the example above) but will not offer to offer to buy drinks/ food or offer to foot his share unless requested.