It is interesting that the two times the Helvetii sent messengers to make a request to Caesar (first to pass Lake Geneva, second to surrender), Caesar told them to wait a number of days for his answer.
In the first instance, he used the time given to build a wall, nullifying their request and showing them that he gives no credence to their ideas and will not operate on their terms. They ask a question, he does not answer. And later on, at the confrontation on the Arar River, Divico barks with underhanded insults, but Caesar does not bark or bite back. A nod of bare acknowledgment by simply accepting their surrender is all Caesar gives the Helvetii, keen to not show his hand and particularly intent to not play their games. He shows he is in charge.
In the last instance, Caesar took advantage of the Helvetii’s fear and destitute state after their loss and retreat into Lingones territory. In response to their offer of surrender, he told them to simply “stay” like dogs. Had he accepted the message, he may have left them off the hook free to move at their discretion. But having them there at a distance, broken – mentally and physically – wait for him like a pup waits for its master worked the effect of imposing his will on them. Should he have told them to “roll over” they likely would have as well. And again, he did not respond to their terms. He did not acknowledge the content of their message at all, but rather used their messenger to send his own word back. He was in charge. He did not take their offer of surrender; they took his offer to surrender.
The Helvetii ended their campaign with one third of their original population having to return home to rebuild the settlements they had torn down themselves, made to look like fools, under Roman yoke.
These are interesting lessons in power plays from a powerful man, but also remember that Caesar overpowered a lot of people along the way and was, ultimately, assassinated by some of them.